Abstract: The aims are to study the motion law of duck in rice field, and clarify the behavioral differences of different duck breeds in rice field and the effect on rice yield. 9 integrated rice-duck farming fields (each one was 766 m2) were selected in this study.‘Yiyong’Duck (Mallard♂?Jinding Duck♀),‘Jinding’Duck and ‘Baigai’Duck were placed in the 9 fields according to the density of 225 ducks/hm2. Using the video monitoring system, the occurrence time and duration time of swimming, resting and feeding of ducks was investigated from 5:00 to 20:00 each day with continuous observation method. The observation was continued for 5 days. The results showed that the activity peaks of the ducks were usually at 5:00 -7:00, 8:00-11:00 and 15:00- 18:00 in one day. The daily activity time of‘Yiyong’Duck and‘Jinding’Duck was 324.50 min (36.06%) and 315.75 min(35.08%), respectively, which was significantly higher than that of‘Baigai’Duck (264.50 min, 29.39%, P<0.01). The rice yield increased by 22.75%, 20.14% and 10.89% in the integrated rice-duck farming with‘Yiyong’Duck,‘Jinding’Duck and‘Baigai’Duck, respectively. The correlation analysis between yield factors of rice and swimming time of ducks showed that there was an extremely significant and positive correlation between the setting rate, theoretical output and swimming time(r=0.959, P＜0.01; r=0.858, P＜0.01). There was an obviously positive correlation between thousand-grain weight, actual yield and swimming time(r=0.627, P＜0.05; r=0.767, P＜0.05). The results indicate that‘Yiyong’Duck has the best effect on yield increasing effect, and the swimming time of duck is an important index for evaluating rice yield in the integrated rice-duck farming system. The results could provide important reference data for the selection of feasible duck breeds and the improvement of rice yield in the IRDF.