|Peaches have soft tissues compared to other fruits and are vulnerable to softness, wounds, and loss of marketability due to the weak fruit hardness after harvest. It is necessary to develop a technology to improve the shelf-life of the fruit to expand the distribution of peaches. Calcium compounds and chitosan have an important role in improving the shelflife of fruit by maintaining the hardness and reducing the respiration rate in peach fruits. In this study, to select useful compounds to improve the shelf-life of peaches, calcium citrate, calcium chloride, calcium nitrate, GH-Ca, OS-Ca, chitosan, and chitosan dissolved in calcium chloride were sprayed onto peach trees. The characteristics of the harvested fruits were investigated after the ‘Kumhong’ and ‘Madoka’ peach tree treatments. The hardness of the fruit was kept the highest with the combined treatment and remained high with the calcium citrate, chitosan and calcium nitrate treatments. Ethylene production and respiration were effectively inhibited by the GH-Ca and chitosan treatments. There was no significant difference in soluble solids content and acidity among the fruits treated with the chemicals. The coloration of the fruit skin was not delayed by the calcium and chitosan chemical treatments. Calcium compounds were increased in the fruits and leaves of the peach trees treated with the chemicals compared to the untreated ones. These results suggest that the calcium treatment extended the shelf-life by increasing the calcium content in the leaves and fruits of the peach trees.