Tomato (Solanum lycopersicum) is one of the most important herbal products that plays an important role in human nutrition and health. Gray mold of Botrytis cinerea and soft rot of Pectobacterium carotovorum are the most important postharvest diseases of tomatoes worldwide. The various methods of chemical, biological and physical are used to control postharvest diseases. The use of chemicals has harmful effects, including lack of selective properties, harmful effects on non-target organisms, endanger human health and the environment and destruction of natural enemies, finding alternative methods is essential. This study was conducted to evaluate the effect of hydrogen peroxide (H2O2) on the control of B. cinerea and P. carotovorum. After disinfection with sodium hypochlorite tomato fruits were inoculated with a suspension of fungi and bacteria. Then the fruits were subjected to various concentrations of hydrogen peroxide. The concentrations of H2O2 used in this study was 1.5, 5, 10, 15 and 20%. Experiments were carried out in the form of a factorial design at a temperature of 20 ± 2 ° C. The diameter of the stains on the fruits was measured by a digital caliper. The results showed that concentrations of 10 and 15% of H2O2, gray mold to 90%, and also 20% H2O2 concentration, completely inhibited the disease. Concentrations of 15 and 20% H2O2 resulted in 90% inhibition soft rot of P. carotovorum in tomatoes. Also, around the wells that were sprayed with hydrogen peroxide after inoculation, necrotic tissue was formed. According to the results and by determining the control of gray mold and bacterial soft rot by hydrogen peroxide, and also the lack of remaining on the fruit retains more pleasure and product reunion. Further studies to manage postharvest disease using hydrogen peroxide as an alternative to Harmful chemical compounds is required.