BACKGROUND: Prostate cancer (PCa) is one of the malignant tumors that seriously affect the health of middle-aged and older men. Chinese medicinal herbs have great potential in tumor therapy with less toxic side effects. 6-C-methylquercetin in the folk medicine Baeckea frutescens, has a good inhibitory effect on human prostate cancer cells (PC3), but its effect and mechanism of anti-PCa have not been elucidated. PURPOSE: This study aimed to investigate the antitumor effect of 6-C-methylquercetin on PCa and its molecular mechanism. METHODS: Network pharmacology was employed to predict the potential targets and pathways of 6-C-methylquercetin acting on PCa, and molecular docking and molecular dynamics simulations were used to analyze the interactions between 6-C-methylquercetin and key target proteins. CCK8, flow cytometry, wound healing, transwell, RT-qPCR, and western blot assay were performed to elucidate the effect of 6-C-methylquercetin on the proliferation, apoptosis, cycle, migration and invasion of PC3 cells, and revealed its regulations on the ErbB/PI3K/AKT pathway. For in vivo experiments, the nude mouse PC3 xenograft model was used, H&E staining, TUNEL, and immunofluorescence assay were performed on tumor tissues, and the biosafety was evaluated by blood routine examination and liver and kidney function tests. RESULTS: Network pharmacological analysis and computational simulations revealed that 6-C-methylquercetin acted on PCa through the ErbBs and PI3K/AKT pathway, and 6-C-methylquercetin had a strong binding affinity for these key node proteins. In vitro experiments demonstrated that 6-C-methylquercetin inhibited the proliferation, migration and invasion of PC3 cells, affected the cell cycle, and induced apoptosis, by suppressing the ErbB/PI3K/AKT pathway activity. Animal experiments showed that 6-C-methylquercetin inhibited the progression of prostate cancer in tumor xenograft mice with a good in vivo biosafety. CONCLUSION: The study first revealed the anti-PCa potential of 6-C-methylquercetin, which may involve the regulation of the ErbB/PI3K/AKT pathway, but its direct targets and specific therapeutic mechanism need to be further explored. These findings suggested that 6-C-methylquercetin had the potential to suppress the development of PCa, and provided a scientific basis for the development and utilization of C-methylated flavonoid compounds from B. frutescens.