Objective To research the method of mice bone marrow mesenchymal stem cells (BMMSCs) trans-differenting into insulin producing cells (IPCs) by rat pancreatic extract (RPE). Methods Mesenchymal stem cells were isolated from Kunming mouse, and RPE was from SD rats’ pancreases. Passaged BMMSCs were induced to be insulin-producing cells (IPCs) with RPE. First, devided mice’s BMMSCs to 6 groups,3 culture flasks per group at random, and added RPE 10mg/L, 20mg/L, 30mg/L, 40mg/L, 50mg/L, 100mg/L to each group. After 1 week, decided which concentration of RPE was better. And induce mouse BMMSCs to IPCs by it (50mg/L). The expression of insulin in IPCs was detected by immunoenzyme cytochemistry and immunofluorescence cytochemistry, the trans-differentiation purity of IPCs was detected by dithizone (DTZ)stain，C-peptide secreting was detected by radioimmunoassay(RIA). Results Mesenchymal stem cells of mice could be induced into IPCs by 50mg/L PRE. Typical islet-like clustered cells were observed after 1weeks, and could be stained scarlet by DTZ.The insulin expression of BMMSCs was positive by immunoenzyme cytochemistry and immunofluorescence cytochemistry. RIA showed the expression of C-peptide in the IPCs could be detected. Conc