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 daily life, such as referential communication. The indirect category learning means that learners interact with their objects and learn category knowledge indirectly.this study designed three experimental tasks (functional prediction task, liberal classification task and dimensions selection task) to explore the influence of the relational complexity upon selective attention during the indirect learning of relational category. The study designed three kinds of experimental materials.The total participants are 216 undergraduate students and they are evenly divided into male and female. They are randomly assigned to the group of indirect category learning of individual functional prediction(72 persons) and the group of indirect category learning relation to referential communication (144 persons).The three experimental tasks were carried out continuously, and the participants involving in functional relation interpretation under the two conditions relating to liberal classification task performed dimensional selection task. Dimensional selection task analyses in a MANOVA . The present study indicated that among dimensions selection tasks of three relational categories the relativity of dimensional number under the referential condition is significantly higher than that under individual condition. With the increasing relational complexity of relational category learning material, there is no significant difference among the results of dimensional selection. The study shows that the influence of the relational complexity upon selective attention during the indirect learning of relational category mainly reflected in the directivity of selective attention and did not reflect in the the concerntration of selective attention (the inhibition of non-relative dimension), the influence of the relational complexity upon overall selective attention was not significant. The participants’ overall level of selective attention under the referential condition was strikingly significantly higher than that under the individual condition, and was not influenced by the relational complexity, which suggest that the influence mainly reflected in the directivity of selective attention and did not reflect in the the concerntration of selective attention.