Sinomenine was found to play anti-cancer functions in different type of cancers, while the mechanisms underlying the anticancer effects of sinomenine in retinoblastoma (RB) remains unclear. The present study was designed to explore the impacts of sinomenine on cell proliferation and invasion ability of RB cells and the related mechanism. Human retinoblastoma cell line WERI-RB-1 and Y79 cells were cultured and treated by different concentration of sinomenine, and then the proliferation ability of the cells was determined via performing the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) proliferation assay. The cell apoptosis was examined via performing the flow cytometry assay. Then scratch wound healing analysis as well as and transwell invasion analysis have been performed to determine the effect of sinomenine on cell migration ability as well as invasion ability. The proteins level of phosphatidylinositol 3-kinase (PI3K)/AKT signaling molecules were determined with Western blot assay. We found that sinomenine was able to decrease the proliferation and promote the apoptosis of RB cells in a dose-dependent manner; moreover, sinomenine also significantly suppressed the migration as well as invasion ability of WERI-RB-1 and Y79 cells in vitro . Furthermore, sinomenine also de-activated PI3K/AKT signaling in WERI-RB-1 cells via inhibited the phosphorylation of PI3K and AKT proteins. Sinomenine can exert anti-tumor function on RB cells in vitro , therefore sinomenine might be a potential alterative medication for the treatment for RB.