Reducing fertilizer application and increasing efficiency are of great significance to the sustainable development of agriculture.This study explored the effects of new synergistic alginic acid compound fertilizers and reduced application treatments on the growth and development of cucumbers，in order to provide reference for the improvement，popularization and application of new synergistic compound fertilizer products.A greenhouse experiment was conducted，and five treatments were set up，including no fertilizer control，conventional compound fertilizer，synergistic compound fertilizer，conventional compound fertilizer reduced by 20% and synergistic compound reduced by 20%.The results showed that:(1)Compared with the conventional compound fertilizer treatment，the synergistic compound fertilizer treatment increased the plant height and leaf area index of cucumber at the seedling，fruit setting，full fruit and final fruit stages.The leaf area index of cucumbers treated with synergistic compound fertilizer increased by 16.3%，8.2%，10.2% and 5.7% at seedling，fruit setting，full fruit and final fruit stage，respectively.The leaf area index of cucumber at seedling stage，fruit setting stage，full fruit stage and final fruit stage increased by 4.7%，0.9%，2.9% and 0.4%，respectively.(2)Compared with conventional compound fertilizer treatment，the underground dry matter mass，shoot dry matter mass and fruit dry matter mass of synergistic compound fertilizer treatment increased by 9.8%，12.6% and 17.7%，respectively，and the shoot dry matter mass and fruit dry matter mass of cucumber treated with synergistic compound fertilizer reduction of 20% increased by 4.8% and 10.8%，respectively.(3)Compared with the conventional compound fertilizer treatment，the nitrogen content of the underground，aboveground and fruit of cucumber treated with synergistic compound fertilizer increased by 16.6%，17.3% and 12.7%，respectively，the phosphorus content of cucumber underground，aboveground and fruit increased by 24.3%，45.4% and 22.4%，respectively，and the potassium content of cucumber underground，above ground and fruit increased by 45.8%，45.7% and 28.9%，respectively.(4)Compared with the conventional compound fertilizer treatment，the yield of cucumber treated with the synergistic compound fertilizer increased by 11.1%.Among all the treatments，the number of cucumbers and the single fruit weight of the synergistic compound fertilizer treatment were the highest.(5)Compared with the conventional compound fertilizer treatment，the vitamin C content of the synergistic compound fertilizer treatment and the 20% reduction of the synergistic compound fertilizer treatment increased by 9.5% and 2.2%，respectively，and the content of nitra nitrogen reduced by 23.8% and 25.1%，respectively.Comprehensively considering the nutrient absorption status，yield and quality of the crops，the synergistic compound fertilizer has the best effect among all the treatments，followed by the treatment of reducing the amount of the synergistic compound fertilizer by 20%，which shows that the reducing treatment of the synergistic compound fertilizer can improve the quality and yield of the cucumber，which has a good prospect for the popularization and application in cucumbers planting.