Today, packaging in the modified atmosphere is used as one of the newest types of packaging to increase the shelf life of fruits and vegetables. Sweet peppers, as a rich source of vitamin C, are one of the most perishable vegetables that require proper transportation and care for shelf life and quality. The shelf life of pepper is limited due to the rapid loss of water during long storage, and the sensitivity to frostbite and common spoilage by Botrytis and Alternaria microorganisms. Therefore, by optimizing the durability of this product, it can be possible to lower a large amount of its waste. In this study, the effect of packaging in a modified atmosphere with three gas combinations containing a combination of conventional gas (which contains 21% oxygen, 0.03% carbon dioxide and 78% nitrogen), the primary gas composition consists of 10% oxygen, 5% carbon dioxide And 85% nitrogen and secondary gas composition consisting of 5% oxygen, 10% carbon dioxide and 85% nitrogen in polyethylene film and maintaining at 8 °C and 95% relative humidity on some properties of belly pepper was evaluated. The effects of these treatments were evaluated in a completely randomized design with factorial experiment and three replications on traits such as weight loss, texture hardness, pH and solids content during 0, 10, 20, 30 and 40 days after harvest. The results showed that, after each storage period, 5% oxygen treated and 10% carbon dioxide treated treatments were better suited for maintaining quality characteristics for pepper, due to more carbon dioxide and lower respiration, and generally keeping the product in packaging with Modified atmosphere, preserving quality and prolonging its shelf-life. [ABSTRACT FROM AUTHOR]