A field experiment was carried out using a cultivar of cabbage that suits the area of Chongqing for cultivation, to study effects of SOP and MOP on yield, quality and nutrients of cabbage, so as to provide a scientific basis for designing a reasonable K fertilizer application technique for production of hazard free cabbage. Results show that application of K fertilizer increased the yield, either biomass or commodity, of cabbage significantly by 4.32%~14.6%. The effects were the most significant in treatments moderate (K2) in K application rate, regardless of forms of potash, and the effects did not differ much between treatments the same in application rate, but different in potash form. But in terms of cost, potassium chloride was superior. K application increased the content of amino acids in cabbage in all the treatments, especially in Treatment K1(S), by 56.9%;decreased VC content in cabbage in all the treatments except for Treatment K2(Cl), which increased the content by 6.8%; reduced nitrate content in cabbage in all the treatments, particularly in Treatment K3(S), by as much as 12.3%; increased reduced sugar content in cabbage in all the treatments with Treatment K1(Cl) in particular; and mineral nutrients, except for Zn, in cabbage to a certain extent in all the treatments. The nutrients in the cabbage were mostly dominated with non-protein forms. Protein-N was significantly and negatively related with amino acid in content in cabbage in all the K treatments, while protein-P was reversely with amino acid, and non-protein-P was significantly and positively related with VC content. Compared with N and P, K, regardless of its form, was more closely related to the quality of cabbage. Total-K and protein-K was in a significantly positive relationship with VC content, but in a negative one with nitrate in the cabbage. To sum up, potassium chloride is a kind of K fertilizer more suitable for cabbage cultivation, preferably at 225 kg hm^-2.