Aiming at the problems of coastal saline soil paddy soil root growth under saline-alkali stress,low nutrient content and low availability. In this research,field experiment was conducted to studythe effects of combined application of phosphate fertilizer and silicon fertilizer on rice root growth,soilphosphorus content,the rice absorbs phosphorus,riceyield,and economic benefits of rice in coastal saline soil. The experiment has twofactors,including two phosphoruslevels: P1: 64 kg/hm²; P2: 128 kg/hm²; silicon fertilizer is divided into soil application and spray application,three levels of soil application:Si1,SiO₂ 0 kg/hm²,Si2,SiO₂ 60 kg/hm²; Si3,SiO₂ 120 kg /hm²; Spray is SiO₂ 15 kg/hm²,and applied with water-soluble multieffect silicon fertilizer (containing water-soluble SiO₂≥30%),which was diluted 500 times per 100 mL and sprayed with 50 L per hectare.The results indicate that the P2Si3 treatment’s total root length,total surface area and total root volume of rice were significantly higher than each other period andit was no significant difference with P2Si4 treatment. Meanwhile,phosphate fertilizer combined with silicon fertilizer can effectively improve the availability of phosphorus in coastal salinized rice soil,the content of available phosphorus in P2Si3 treatment was significantly higher than that in P1Si3 and P2Si1,respectively higher 35.16% and 27.47%; the total phosphorus content of soil treated with high phosphorus fertilizer was higher than that treated with low phosphorus fertilizer. Moreover,rice yield with P1Si3 and P2Si4 treatment was significantly higher than that P1Si1 and P1Si2 treatment,the yield of P2Si3 treatment was 9 547.5 kg/hm² there was no significant difference in the effective spike number of each treatment,P2Si3 treatment was the highest with 162.47 grains per panicle. P2Si3 treatment’s accumulation of p in rice grains and was significantly higher than other treatments,compared with P1Si3 and P2Si1,it was 8.46% and 9.68% higher respectively. Under low or high phosphorus level,P1Si4,P2Si4 treatment’s income reached 14 953.6 CNY/hm² and 14 323.2 CNY/hm².In conclusion,compared to the treatment without silicon fertilizer,the application of silicon fertilizer can significantly promote the root growth of rice,phosphorus availability,rice yield and economic benefit in coastal salinized soil,among them,P2Si3 treatment (silicon sprayed on the blade,P₂O₅ 64 kg/hm²) is the best treatment.