Objective. To investigate the inhibitory effect of ethyl acetate extracts of Impatiens balsamina L. on prostate cancer cells. Methods. Impatiens balsamina L. was extracted to get water, ethanol, oil ether, ethyl acetate, and butanol extracts. CCK-8 assay was used to detect the inhibitory effect. Apoptosis rates and cell cycle distribution were detected by flow cytometry. Transwell assay was performed to test the ability of migration. The expressions of Bcl-2, Bax, cleaved-caspase-3, p-ERK, ERK, p-AKT, AKT, cyclin D1, cyclin E, and MMP2 were detected by Western blot. Results. Ethyl acetate extracts had the strongest inhibitory effect. After being treated with different concentrations of ethyl acetate extracts, the percentage of G0/G1 phase increased significantly, cyclin D1 and cyclin E expression decreased, apoptosis rate was significantly higher, and the ability of migration of PC-3 and RV1 was inhibited significantly. Western blot showed that the expressions of Bcl-2, p-ERK, and p-AKTwere significantly decreased, but the expressions of Bax and caspase-3 cleavage were increased. Conclusions. Impatiens balsamina L. inhibited the proliferation of human prostate cancer cells; ethyl acetate extracts have the strongest effect. It could inhibit cell proliferation and migration, cause G1 phase arrest, and induce apoptosis probably through inhibition of the AKT and ERK pathways.