Abstract: Objective: To explore the affecting factors of intelligence on middle school students.Methods: Intelligence quotients(IQ) of 198 middle school students were measured with Wechsler intelligence Scale for Children-Revised(WISC-R) and the factors that affect IQ were analysed.Results: IQ distribution in these students was normal.There was no sexual difference in the verbal intelligence quotient(VIQ),performance intelligence(PIQ) and full intelligence quotient(FIQ)(P>0.05).The intelligence of student that had a hobby was higher than that of student without a hobby(P<0.01).There was obvious difference in IQ of differ school's student(P<0.05).Through multilane regress,factors of affecting IQ include hobby,mother's and father's education level,father's job,school and age.Conclusions: That raising parents' education level and training children's hobby are significant for the development of middle school students' intelligence.