Pot experiments with winter wheat were conducted to investigate K content characteristic of main growth stages of winter wheat in soil with different K fertility, and analyzed the correlations between different part K contents and whole plant K content, K uptake of maturity stage. The results showed that K content of wheat gradually reduced during whole growth period, and it increased with increasing soil K fertility. The characteristic of K content of wheat was different in different growth stages, jointing stage, the K content of leaf and sheath gradually reduced from upper leaf position to lower position, namely, 1st leaf > 2nd leaf > 3rd leaf > 4th leaf, 2nd sheath > 3rd sheath > 4th sheath, drop range of sheath reduced with rising soil K level, booting stage, in low and middle K level, K content of spike of wheat was highest, K contents of leaf and sheath gradually reduced from upper leaf position to lower position, namely, 1st leaf > 2nd leaf > 3rd leaf > 4th leaf,1st sheath > 2nd sheath > 3rd sheath > 4th sheath, in high K level, there was no significant difference between K content of spike of wheat and K content of different leaf position, K content of 2nd sheath was low; heading stage, K content of different leaf position had no significant difference, but for K content of 1st was significantly higher. The correlation analysis showed that booting stage and jointing stage was the good stage for wheat K nutrition diagnosis, 1st leaf, 2nd leaf, 3rd leaf were the sampling parts of K nutrition diagnosis at booting stage and jointing stage. K content ratio of 1st leaf and 4th leaf could be used for K nutrition diagnosis of wheat.