Objective To understand the characteristics and rules of behavior and preliminary study on the change of psychological state and behavior of infant rhesus monkeys after weaning by artificial feed. Methods 290 infant rhesus monkeys were born in 2012, individual behavior of infant rhesus monkeys were observed and recorded by the methods of ad libitum sampling and chronography. Results The behavior of huddling, sucking finger and sucking body of companion were observed in the first month, the behavior of huddling and sucking finger were significantly increased in the second and third month(P< 0.05), sucking body of companion in second month were significantly higher than the first month(P< 0.05); the new behavior pacing, sucking genitalia and mounting were observed in the second month, pacing and sucking were significantly increased in the third month(P< 0.05), mounting did not have obvious change; in the third month, sucking toe behavior ware recorded and did not change with time; The proportion of huddling behavior occurred between female and female was significantly higher than opposite sex or male in the same cage. The male infant monkeys were more likely to occurred pacing behavior than female. Sucking body of companion and sucking finger behavior of male were significantly lower than the female infant monkeys (P< 0.05). There was no significant difference of sucking toe behavior. Conclusions 7 behaviors were recorded during the whole stage of observation, huddling behavior, pacing behavior, sucking toe behavior, sucking finger behavior, sucking genitalia behavior, sucking body of companion behavior and mounting behavior respectively, and 7 behaviors were increased by degrees with time. Huddling behavior to reflect fear psychology; sucking behavior to represent physiological demand and defensive psychology; pacing was insignificant behavior in the initial stage, then to reflect psychological anxiety of rhesus monkeys. Provided a way and model on assessment of psychology, praxiology, to study and research the change of psychological state and behavior of early weaning infants.