Abstract: In summer and autumn of 2003, the author introduced target objective observation and scan sampling methods to research the behavior coding and rhythm of Chinese alligator, Alligator sinensis. The results showed that the main individual behaviors include resting behaviors( resting in water, resting on land, basking yawning, stretching waist, tickling), sport behaviors (swimming, diving, crawling, swing tail),feeding behaviors(feeding, gargling), conflicting behaviors (fighting, staring) playing behaviors ( pileup , playing) , roaring behaviors and so on. After reproduction in summer, resting is the main behavior of daily rhythm, basking becomes the main behavior in autumn. The dally varying rhythm of main behaviors of Chinese alligator showed that from 6:00 to 7:00 in summer morning,there is a resting fastigium and a diving fastigium from 12:30 to 13:30 in the afternoon. In autumn, there was a diving fastigium from 6:00 to 7:30 and three basking fastigiums in a day,that was 10:30-11:00,13:30-14:00,16:30-17:00.The analysis showed there were significantly differences among the diving,basking and resting in summer and autumn.During the temperature of 30℃-36℃,the relationship between diving time and temperature approximately abide by linearity relations. During the temperature of 25℃-30℃, the temperature was not the most important factor. Because of the long time breeding, some elastic behaviors,such as feeding,were affected very much. Except for the description for behavior,this paper also discussed the mechanism of behaviors. Biological factors affecting alligators' behaviors were described, including age and food resources. Non-biological factors were demonstrated also in the study,such as space and living habitats.