India is the world's second-largest producer of onions. In addition to being a vegetable, the onion is among the fruits and vegetables that contributes significantly to foreign exchange earnings. Onions can rot or decay, however, as a result of the ongoing climate change. As a result, onions should be kept fresh by keeping the temperature suggested by Onions are kept in storage at a temperature of 0 to 4°C and a humidity of 60 to 70% in the ambient environment. Thus, the concept of onion preservation has emerged. In this project, we are creating an onion preservation system that keeps onions from spoiling. Sensors for temperature and humidity have been employed in this system to track the two variables. Carbohydrate for out-side onion in range 8.0- 8.7 mg and Carbohydrate for stored onion in range of 11.0-11.4 mg. Vitamin C for out-side onion in range of 4.5- 4.8 mg and Vitamin C for stored onion in range of 5.7-6.0 mg.