Objective: To investigate the effect and mechanism of emodin (EMO) on human pancreatic cancer cell line BxPC-3 in vivo. Methods: After the pancreatic cancer model in nude mice was established, the mice were divided into four groups: control group (NS 0.2mL/d by i.p. injection), EMO group (EMO 40mg?kg-1?d-1 by i.p. injection), and Gemcitabine (GEM) group (GEM 80mg/kg, twice/week by i.p. injection) with 8 mice each group. After 2 weeks of administration, the mice were sacrificed, detected the body-weight change of nude nice before and after the experiment, and recorded the growth inhibition rate of tumor (TGI). Immunohistochemical (IHC) staining for ki-67 and terminal deoxynucleotidyl transferase-mediated nicked labeling assay (TUNEL) were undertaken to detect the cell proliferation and cell apoptosis in tumor tissue in xenograft nude mice. Results: The inter-group comparisons in body-weight of nude mice showed no significant difference in comparing group NS(27.0?1.64)g with group EMO(25.1?1.58)g and GEM(25.6? 1.47)g.The EMO group was 38.46%, the GEM group was 44.23%. The inter-group comparisons in immunohistochemical analysis of ki-67 showed significant difference in comparing group NS IOD(219.5?17.98) with group EMO IOD(146.6? 11.57)and GEM IOD(139.5?12.55), (P