"Relational category" means that identification of category is determined by a common relation structure. People are more inclined to use indirect means to learn category knowledge in real life, such as referential communication. "The indirect category learning " means that learners interact with their objects and learn category knowledge indirectly. Previous studies mainly focused on the characteristics of category learning by "the direct category learning" paradigm. Thus, this study designed three experimental tasks (functional prediction task, liberal classification task and dimensions selection task). The purpose is to explore the indirect learning characteristics of 4 features’ complex relational category by the referential communication learning paradigm. The study designed four features (foot, mouth, hand, eye) virtual alien as experimental materials, each feature has two values(0,1). Three dimensions of virtual alien contain two functional relationships: a simple functional relationship-absorbing water and a complex functional relationship-generating electricity. And simple relationship is contained within complex relationship. The fourth dimension is the interference dimension. Four permutations of these physical features—A. foot, mouth, hand, eye; B. eye, hand, foot, mouth; C. eye, hand, foot, mouth; D. eye, hand, foot, mouth—were assigned in order to eliminating influence on expectations on features or functions of the participants. 96 undergraduate students participated in the current study, evenly divided into male and female, and they were grouped in a random manner. The study used the indirect category learning paradigm-individual indirect category learning condition (24 persons) and referential communication category learning condition (48 persons), and a non-functional predictive learning condition (24 persons). The three experimental tasks were being continuously. The interpretation result of liberal classification explores whether the relations in indirect learning process more salient than features when both acting as category standard by a chi-square test. The result of functional prediction explores that between referential communication learning and individual indirect learning, which one is more effective by a repeated-measures ANOVA of the function prediction accuracy rate. The result of dimension selection explores whether the level of the selective attention of the participants under the conditions of referential communication is significantly higher than that under the individual conditions by a t test. The research found out that with respect to interpretation type of liberal classification result, the participants under the condition of category’s indirect learning are more inclined to select functional relations as the standard of classification while the participants under the condition of non-functional prediction learning are inclined to choose the standard of feature. In the functional prediction learning process, the participants under the condition of referential communication scored significantly higher points than individual condition, and it began to emerge from the fifth learning stage. When it comes to dimension selection task, the average number of biological dimension revealed under the condition of referential communication is significantly greater than that under individual condition. Specifically speaking, there is a strikingly stark difference between the number of relative dimension relating to the participants under the two learning conditions; the things are opposite to the above with respect to that of non-relative dimension. The study shows that in terms of liberal classification task, the participants are more inclined to choose the relation as the standard of category under the condition of indirect learning of category; The learning effect of referential communication condition is significantly better than that of individual condition during the functional prediction process, and such difference is mainly embodied in the middle and later term of learning process in relation to the formation of referential convention rather than in the earlier time of the process; The level of selective attention of the participants under the condition of referential communication during the indirect learning of relational category process is significantly higher than that under individual condition, and such difference is characterized as directivity of selective attention rather than concentration of selective attention (the inhibition of non-relative dimension). Referential communication promotes the indirect learning relating to 4 features’ complex relation category.