Abstract: Abstract: Precipitation is an important factor affecting the efficacy of the copper fungicides. The purpose of this study was to explore the leaching loss of copper-based protective agent (CPA) spraying on the leaves of eggplant (Solanum melongena L.) and its effects on the growth of eggplant under different simulated rainfall intensity. The traditional Bordeaux mixture (BDM) was considered as a control. A pot experiment of eggplant was conducted at an intelligent greenhouse of Shandong Agricultural University from July to October in 2015, to investigate the leaching rate of CPA on eggplant leaves and its effects on disease control of gray mold, yield, biomass, available copper content and total copper content in soil under the situation of spraying BDM and CPA under simulated rainfall intensity of 0, 17.1, 33.7, and 58.7 mm/h. The tests were performed with 9 treatments with 4 replicates. The BDM and CPA were used in the regular amount. The results showed that the surface tension of CPA was decreased by 37.0% and 33.4% respectively, compared with the surface tension of deionized water and traditional Bordeaux mixture. The contact angles between CPA and eggplant leaves were decreased by 28.1% and 31.2% in comparing with that of deionized water and BDM. At the seedling stage, initial flowering stage and fruit stage of eggplant, compared with the BDM treatments, the leaching rates on eggplant leaves in CPA treatments under the simulated rainfall intensity of 17.1 mm/h were significantly decreased by 33.2%, 10.2%, and 32.0%, respectively; the leaching rates under the simulated rainfall intensity of 33.7 mm/h were decreased by 19.3%, 15.2%, and 19.2%, respectively; the leaching rates under the simulated rainfall intensity of 58.7 mm/h were decreased by 15.5%, 11.5%, and 20.9%, respectively. At the fruit stage, compared with BDM treatment, the disease control effect of CPA treatment on gray mold was increased by 51.6% under no rainfall situation; the control effect on gray mold of the CPA application under the simulated rainfall intensity of 33.7 and 58.7 mm/h increased by 70.8% and 181.0%. The use of CPA also significantly increased the plant height, stem diameter and biomass of eggplant at fruit age of eggplant. At fruit stage, under no rainfall situation, the available copper content in soil sprayed with CPA was remarkably reduced by 18.8% when compared with BDM treatment. But for the total copper content in soil, there were no significant difference among all those treatments. Under the simulated rainfall intensity of 17.1, 33.7, and 58.7 mm/h, CPA significantly decreased the available copper content in soil by 23.9%, 41.8%, and 45.3%, respectively, and also decreased the total copper content of soil by 4.3%, 9.1%, and 18.0%, respectively, when compared with BDM treatments. These results demonstrate that spraying with CPA on the leaves of eggplants under the simulated rainfall intensity of 17.1, 33.7, and 58.7 mm/h not only significantly decreases the leaching rate of protective agent, promotes the control effect of gray mold and increases the yield and biomass of eggplant, but also reduces the accumulation of copper in the soils.