The water footprint theory was employed to accurately evaluate the water resources utilization efficiency of Guyuan potato production in order to provide a theoretical support for the development of local potato industry. The Penman-Monteith equation based on actual water consumption, Mann-Kendall trend test, Sen’s slop and logarithmic mean Divisia index (LMDI) model were adopted to analyze the variation trend of potato water footprint (PWF) and its contributing factors. The results showed that the average PWF in Guyuan City during 1981-2017 was 1.48 m3/kg, and in its subordinate counties was between 1.17 and 2.04 m3/kg, which all showed a decreasing trend, with an average annual variation of -0.04 m3/(kg·a) in the City. The green water consumption per hectare (CWUgreen) and the average yield per hectare (Y) were 2 778.4 m3/hm2 and 2.18 t/hm2, respectively; whereas those of subordinate counties were in the range of 2 622.2-3 401.3 m3/hm2 and 1.65-3.19 t/hm2, respectively. The Y in the subordinate counties all showed a significant upward trend. From northwest to southeast, the Y and CWUgreen increased, but the water footprint decreased. The contribution rate of Y for changes in PWF during the whole period was 80.8%, and the contribution amount was in the range of 0--2.30 m3/kg. The contribution rate of CWUgreen was 19.2%, whereas in the subordinate counties the contribution rates of Y were in the range of 76.3%-84.0%, and those of CWUgreen were in the range of 16.0%-23.7%.The water footprint calculation method adopted here is based on the actual water consumption condition, which can reflect the real situation better than the full irrigation condition. The increase of Y contributes the most to the significant decrease of PWF in Guyuan, which still has potential to improve. Therefore, the local government and farmers should strengthen the development of agricultural modernization and improve the utilization efficiency of water resources to increase the yield.