Studying the effect of different nitrogen（N）application rates on soil phosphorus（P）transformation and their microbial mechanisms could provide theoretical support for optimal nutrient management in potato production. The N fertilizer management experiment of potato continuous cropping system was conducted in 2017 at the Wuchuan Dryland Experiment Station in Inner Mongolia Autonomous Region，four treatments included NE（fertilizer dosage recommended by NE ）， NE-N，NE-1/2N，and NE+1/2N. Soil samples in the 0-20 and 20-40 cm soil layers，and potato straw and tuber in each treatment were collected at potato harvest period in 2023，soil N and P contents，phosphatase activity，and the abundance of its encoded genes，and P uptake in potato straw and tuber were determined. Compared with the NE-N treatment，the NE1/2N，NE，and NE+1/2N treatments reduced total P，organic P，and available P of the 0-20 cm soil layer by 10.0%-20.3%， 7.5%-18.8%，and 38.9%-52.7%，respectively. However，only available P significantly decreased by 17.4%-25.1% in the 20-40 cm soil layer. With the gradual increase of N fertilization rates，the N/P ratio of 0-20 cm soil layer gradually increased and the pH gradually decreased，while there was no significant change in the N/P ratio and pH of surface soil. The activity of soil alkaline phosphatase and the abundance of its encoded genes phoD and phoX showed an increased and then decreased change with the increasing N application rates. The NE treatment had the highest alkaline phosphatase activity in both soil layers，and the activity in the 20-40 cm soil layer was higher than that in the 0-20 cm soil layer in the same treatment. The phoD presented higher abundance than phoX in the same soil layer. Correlation analysis showed that the abundance of soil phoD and phoX genes and alkaline phosphatase activity were significantly negatively correlated with available P content. In summary，optimizing N fertilization was beneficial for soil P conversion and utilization in potato production in arid and semiarid regions.