Objective  To find a polymer biomaterial suitable for bone marrow mesenchymal stem cell (BMSC) growth as a myocardial patch. Methods We obtain mouse BMSCs from clean grade healthy male C57 mice and identify the cells as CD34, CD45 negative, CD90 weakly positive and CD73 positive by flow cytometry. Cultured after five generations, BMSCs are co-cultured with polyurethane(PU), 3-hydroxybutyrate-co-4- hydroxybutyrate ［P(3HB-co-4HB)］ and polycarbonate class (PC) (n = 6) for 24 h, fixed for scanning electron microscopy and are stained with DAPI fluorescent dye, observed under fluorescence microscopy for cell count. Results The cell morphology of the PU patch and the P (3HB-co-4HB) patch are normal and the quantities of cells are large in the scanning electron microscope. The surface of PC patch is smooth with small quantity of BMSCs, cell debris and cell lysates. The difference of cell counts between PU group and P(3HB-co-4HB) group under the fluorescence microscope is not significant analyzed by one-way ANOVA with SPSS 12.0 software. The differences of cell counts between the PC group and the PU group, the PC group and the P(3HB-co-4HB) group are statistically significant (P<0.05). Conclusions PU material and P (3HB-co-4HB) material are both fit for BMSCs co-culture. With the nature of good tissue compatibility and biodegradability, P(3HB-co-4HB) is to be used as cell cardiomyoplasty surgery cardiac patch material.