This field experiment was conducted with different varieties of potato ("Atlantic" "Purple Potato" "Ji Zhang Potato 12") in Zhangbei area to explore the effects of microbial inoculants with P and K-solubilizing bacteria (MI containing the effective strains of Bacillus megaterium and Bacillus mucilaginous) on potato yield, quality, soil available P, K and soil phosphatase. The results showed that the application of microbial inoculant increased the yields of three varieties of Potato (P<0.05), especially for "Ji Zhang Potato 12"by 24.54%, while the average increase of yield was only 6.96% for the other two. Moreover, the quality of potatoes was improved, especially for Purple Potato. The contents of Vc, soluble protein and soluble sugar were significantly increased by 320.21%, 29.40% and 7.12%, respectively (P<0.05). In addition, the application of microbial inoculant regulated the contents of available phosphorus and potassium in the soil and the related soil enzymes activities during the whole growth period. The available P and K contents of the soil cultivated with the cultivars of "Atlantic"and "Ji Zhang Potato 12"were higher than those of CK, and reached a significant level at the middle and late growing stages. At the same time, the activities of soil acid and alkaline phosphatase were increased, with an average increase of 37.52% and 32.30% respectively. Overall, P and K-solubilizing microbial inoculant is suitable for the growth of potato in Zhangbei area, especially for "Ji Zhang Potato 12".