The maternal behavior of sows in the perinatal period directly affects the survival rate of piglets, and the posture of the sows is an important manifestation of its maternal behavior and nesting behavior. Current perinatal sow’posture transformation mainly relies on manual observation, which is time-consuming, labor-intensive and subjective. Aiming to recognize sows'stand, sit, sternum, lateral and lateral directions totally 24 sows’ video were collected and the data pre-processing research was performed, and the EfficientDet network was used to perform deep feature extraction on the image of sows in the farrowing bed. The breast facing the heat lamp for piglet and the breast averting the heat lamp were included. The results showed that the average recognition accuracy (mAP) of the algorithm was 93.97%, the detection speed of pictures was 26.2f/s, and the detection speed of videos was 10.66f/s. By analyzing the postpartum of sows before and 24 hours after delivery, sows showed significant nesting behaviors before delivery, and the frequency of posture changes was increased obviously(P<0.001). Sows' lateral time after delivery was increased significantly, there was a positive correlation between the length of lateral time and the average weight of the piglets. The sows were grouped according to the preference of the lateral direction. When the sows tended to lie with breast facing the heat lamp, the piglets’ survival rate was higher.