Abstract: The cauliflower was used as experimental material,the effects of phosphorus application on root layer phosphorus quality,yield of cauliflower,cumulative distribution of phosphorus in plants,phosphorus utilization efficiency and apparent balance of open field soil were studied by using single factor random block field test method,in order to determine the optimal phosphorus application level in cold and cool cauliflower production in southern mountainous area of Ningxia.The results showed that phosphorus application significantly increased the yield of cauliflower,with an increase rate of12.96%-22.08%.The relationship between phosphorus application level and flower bulb yield was very significant quadratic parabolic curve.When the maximum yield was 3 651.12kg per 667m~2,the optimal phosphorus application level was 24.28kg per 667m~2.At seedling and rosette periods,stems and leaves were the accumulation centers of phosphorus in cauliflower,and the distribution ratio of stems and leaves under different treatments was 69.79%-86.08%.At maturity stage,flower bulb was the accumulation center of phosphorus,and the accumulation ratio of phosphorus in flower bulb was 53.61%-72.95%,with P₁₀treatment being the highest.The phosphorus accumulation of the whole plant was significantly increased by 46.15%compared with P₀treatment without phosphorus fertilizer.The utilization efficiency of phosphorus fertilizer was 13.01%-33.78%,and the utilization efficiency of phosphorus fertilizer in P₁₀treatment was the highest,which was significantly higher than that in other treatments,and the contribution rate of phosphorus fertilizer was 19.03kg·kg^-1.When the phosphorus application level was less than 10kg per 667m~2,the soil phosphorus balance showed a deficit;when the phosphorus application level was more than 15 kg per 667 m~2,the apparent phosphorus balance showed a phosphorus surplus.Considering the yield of cauliflower,phosphorus utilization and soil phosphorus budget balance,it was suggested that the suitable phosphorus application level of cauliflower in the southern mountainous area of Ningxia was 12.61-12.86kg per 667m~2.