To explore Childhood amnesia phenomenon, the previous studies mostly investigated on western adults.However, in recent years, some cross-cultural studies and children studies discovered age and cultural factors have a significant effect on the boundary of childhood amnesia .Moreover, memory emotion was limited to be measured by emotional valence and emotional intensity, thereby restricting the discussion about the emotion mechanism of autobiographical memory. From the perspective of development, the study uses the single earliest memory method to investigate child-only’s childhood amnesia .Firstly, the research revised the single earliest memory method by referencing literature and conducting pre-interview. Then, the formal investigation used a revised interview approach, which investigated 60 students from grade 4 in primary school and grade 2 in middle school. The detailed procedures of interview are as follows.Firstly, the subject was introduced to the standard of memory, which stressed that the memories reported must be a specific memory and be able to remember. Secondly, the subject was required to report his/her earliest memory after taking a three-minutes recall. Meanwhile, he or she was also required to provide an estimate about his or her age of the earliest memory just recalled. After that, an opening question was introduced stating “ what did you feel like during the developing process of the whole event”. The last step is the examination of adjective check list. This survey is consisted of moral emotion words from Haidit’s Moral Emotion Model and other six common basic emotion words. After interview, the following step was coding the content of the interview. Coding methods are mainly based on the classic study. What worthwhile to be mentioned was the analysis of the emotional content in memory. Specifically, from the stage of the opening question, the content reported by the subject would be coded as positive, negative, neutral or mixed emotion. In addition to it, the words selected by the subject from adjective check list would be coded as the moral emotion and the basic emotion, which would be scored accordingly. The research results show as follow: (1) In general, gender differences and age differences of the children's earliest memory are not significant，apparently, they showed consistency.The mean age at the earliest memory across the entire sample is 41.15 months.（2）There are significant correlations between mentions of emotions and memory volume.( p<.001)（3）The basic emotion（M=1.46,SD=0.89）from earliest memory is significant higher than moral emotion（M=0.83,SD=1.02），t（59）=3.70，p<.001. (4) The percentages of moral emotions and mixed emotions in autobiographical memory,are 53.7% and 41.7% respectively. The finding suggests that Chinese children in urban at age of 9 years old already resemble adults. The high emergence frequency of moral emotion and mixed emotion in the earliest memory indicates understanding emotion possibly plays a key role in the further loss of early memory in the middle period of childhood. The development of emotional ability shall be further studied as the mechanism of the childhood amnesia.