Abstract: Potato is one of the main crops in Ulanqab, but the potato continuous cropping obstacle is becoming more and more serious, which has already affected the sustainable development of the industry. The local major cultivar‘Houqihong’, as the experiment material, was planted in rotation, one year continuous cropping and two years continuous cropping. Photosynthetic performance related indexes and soil available nitrogen content were investigated every 15 days from 33 days after emergence. The results showed that the change trend of leaf area index (LAI ), relative chlorophyll content (SPAD ), photosynthetic rate (Pn ) and transpiration rate (Tr ) were same for the three treatments with the advance of the growing period. Compared with the control, leaf area index (LAI ), relative chlorophyll content (SPAD ), photosynthetic rate (Pn ) and transpiration rate (Tr ) were reduced significantly for two year continuous cropping at some growing periods, while had no obvious change for one year continuous cropping. The content of soil available nitrogen of control was significantly higher than those of two years continuous cropping after emergence, while that of one year continuous cropping had no big difference. And correlation analysis indicated that the content of available nitrogen was positively correlated with the index of photosynthetic characteristics. Therefore, it is conducive to improve the photosynthetic characteristics when nitrogen fertilizers are rationally increased in soil, especially at the middle and late growing stage.