product areas of potato are mainly in Hei Longjiang province Ke Shan county in china. by way of experiment for two years, we research how to influence production and related character by applying potassium fertilizer in different growth stages of potato. The result proved, applying potassium fertilizer can in crease production of potato, content of amylum and marketable rate. It can increase the content of chlorophyll and photosynthesis intensity in later period of growing stage, and it also can delay the senile in later period of growing stage, extend the growing stage. Applying potassium fertilizer has different effect in different period, but the best effect is in the initial stage of appearing flower bud.