The purpose of this paper was to explore the best mixed application mode of polyphosphate and conventional watersoluble phosphate fertilizer in drip-irrigated cotton field， in order to achieve the purpose of economic and efficient utilization of phosphate fertilizer. Under equal phosphorus application (P2O5 120 kg/hm²)， the ammonium polyphosphate 1 (APP1)， ammonium polyphosphate 2 (APP2) and potassium tripolyphosphate (KTPP) were mixed with water-soluble diammonium phosphate according to three different ratios to form 9 kinds of polyphosphate fertilizers. In these 9 polyphosphate fertilizers， 10%， 30% and 50% of the total P2O5 came from APP1， APP2 and KTPP， respectively， which were expressed as APP1-10， APP2-10， KTPP-10， APP1-30， APP2-30， KTPP-30， APP1-50， APP2-50 and KTPP-50. At the same time， conventional water-soluble diammonium phosphate treatment without polyphosphate (DAP) and no phosphate fertilizer (P0) were used as controls. The soil available phosphorus contents at 0–20 cm and 20–40 cm soil depth， biomass and phosphorus uptake of drip irrigated cotton were measured at full flowering stage and boll stage. At the same time， the boll setting dynamics of cotton was monitored， and the yield and yield components were determined at the mature stage. The soil available phosphorus content in 0-20 cm， cotton shoot biomass， phosphorus uptake of cotton， boll number per plant， seed yield， boll number before dog days， phosphorus agronomic utilization rate and output-input ratio increased with the increase of polyphosphate blending ratio. In terms of increasing soil available phosphorus content， cotton shoot biomass， phosphorus uptake of cotton， boll number per plant， seed yield， the boll number before dog days， phosphorus agronomic utilization rate and output-input ratio， the overall performance of three different polyphosphates was that APP2 treatment was the best， followed by KTPP treatment， and finally APP1 treatment. At the full flowering stage and boll stage， the soil available phosphorus content in 0-20 cm soil and phosphorus uptake of cotton in APP2-50 treatment were significantly higher than those in DAP and other phosphorus application treatments， while 20–40 cm soil available phosphorus content had no significant difference among all fertilization treatments. There was no significant difference in cotton biomass between APP2-50 and DAP treatment at full flowering stage， but at boll stage， the biomass of cotton in APP2-50 treatment was significantly higher than that in DAP and other phosphorus treatments. The boll number of cotton treated with polyphosphate fertilizers was significantly higher than that of DAP， but there was no difference in cotton boll weight among different phosphorus application treatments. The seed yield， phosphorus agronomic utilization rate and output-input ratio of APP2-50 were the highest. Compared with DAP， APP2-50 treatment increased seed cotton yield， phosphorus agronomic utilization rate and yield-input ratio by 10.7%， 88.3% and 7.6%， respectively. The above results show that the mixed application of APP2 treatment with water-soluble diammonium phosphate according to 50% of the total phosphorus content of P2O5 can increase thecontent of available phosphorus in drip-irrigated field， and has a positive effect on the increase of cotton yield and the ratio of output to input. It is a fertilization choice with both high efficiency and economic application of phosphate fertilizer.