Abstract: Taking tomato as the test material, and a pot experiment was used to study and compare the effects of adding different types and different concentrations of synergists to water-soluble fertilizers on tomato growth and fruit, in order to provide a certain reference for actual production and pave the way for more in-depth applications of chitooligosaccharides and alginic acid in agriculture.The results showed that the effect of adding 0.4% chitooligosaccharide in the early stage of fruit bearing was the best, which significantly increased the number of fruit in the early stage of fruit bearing.Adding 0.1% chitooligosaccharide in the reproductive growth period of the fruit had the best effect, which could significantly increase the fruit transverse diameter, yield and color change rate.The soluble solids and soluble sugars of tomato in this experiment did not differ significantly between the treatments, and the vitamin C content of the fruits treated with each added amount of each synergist was significantly higher than that of the control treatment.However, based on the average value of adding various concentrations of chitooligosaccharides and alginic acid, the addition of alginic acid was more conducive to the accumulation of vitamin C in the fruit.