Abstract: The effect functions of NPK application on economical yield, fertilization benefit and N ratio of split application at different growing periods of cauliflower(Brassica oleracea var. botrytis) were studied by the field experiments with 311-A best regression design of supposed saturation and {3, 2} saturated design of single shape check. The results showed that the best NPK application of cauliflower with maximum economical yield of 54.877t/hm2 was N249.28, P2O554.33 and K2O 238.83kg/hm2, the best NPK application with the best fertilization benefit of 63784.89 yuan/hm2 and higher economical yield of 54.853t/hm2 was N243.52, P2O552.22 and K2O 234.09kg/hm2, and betterratio of N split application as basal dressing, former and latter topdressing for higher expecting economical yield of 55.313t/hm2 was 0.3135:0.4500:0.2365, and the N rates were 76.49, 109.80 and 57.71kg/hm2, respectively. Under equal fertilizer, there was the negative correlation between vitamin C, reducing sugar and total sugar content of cauliflower and N application on certain level, with PK application the positive correlation; And the nitrate content with N application the positive barrier that submits certain level , with PK application the negative correlation of considerable level. In PK application the condition with identical quantity take off, N application the later or latterdressing the bigger, vitamin C, reducing sugar and total sugar content of cauliflower are the more lower, but the nitrate content is higher.