The aims of this research are to know the effect of silica fertilizer (Si), salt stress and their interactions on the agronomic characteristics of tomato plants on Entisol soil. The experiment employed factorial randomized complete block design (RCBD) with 2 factors experiments i.e. level of conductivity, namely K0 = 0ds/m / pot, K1 = 1ds/m / pot, K2 = 2ds/m/pot, and K3 = 3ds/m/pot, and doses of Si fertilizer, namely S0 = 0g/pot, S1 = 5g/pot, S2 = 10g/pot, and S3 = 15 g/pot. There were 16 treatment combinations with 3 replications, in total 48 experimental unit were used. The variables observed were plant height, number of leaves, chlorophyll content, flowering age, number of flowers, number of fruits, fruit weight, and fruit volume. The application of Si fertilizer increased the number of tomato flowers. Salinity stress reduced plant height and weight of tomatoes. The interaction of silica fertilizer (Si) and salt stress influences the number of leaves and the number of flowers. The highest number of leaves was at the dose of KCl 1 ds/m/plant and silica fertilizer 5 g/plant, while the highest number of flowers was at the dose of KCl 3 ds/m/plant and silica fertilizer 10 g/plant.