Objective To prepare a microRNA (miRNA) delivery system using the branched polyethyleneimine (BPEI), linear polyethylenimine (LPEI) and polyamidoamine dendrimers (PAMAM) loaded with miRNA-15a and miRNA-16-1, which can inhibit prostate cancer PC3 cell proliferation, and to examine the zeta potential, intracellular uptake, and the inhibition effect on PC3 cells of the three constructed nano-complexes. Methods Particle size analyzer was used to determine the size and potential of the three kinds of nano-complexes, and the miRNA affinity capability of them was determined by agarose gel electrophoresis retardation assay. The uptake efficiency of the nano-complexes by PC3 cells was examined by NC-miRNA labeled with FAM. CCK8 method was used to determine the inhibitory effect of the nano-complexes loaded with miRNA-15a and miRNA-16-1 against PC3 cells, and PCR was used to analyze their inhibitory effect on expression of Bcl-2, Cylin D₁ and Wnt3a gene in PC3 cells. Results BPEI, LPEI and PAMAM loaded with miRNA could form stable nano-complexes. When N/P=5, the intracellular uptake of BPEI/miRNA-FAM by PC3 cells was significantly higher than that of LPEI/miRNA-FAM and PAMAM/miRNA-FAM (P<0.05). BPEI, LPEI and PAMAM could all carry miRNA-15a and miRNA-16-1 into PC3 cells and block Bcl-2, Cylin D₁ and Wnt3a expression in PC3 cells. Conclusion BPEI, LPEI and PAMAM loaded with miRNA-15a and miRNA-16-1 can suppress proliferation of prostate cancer PC3 cells and block Bcl-2, Cylin D₁ and Wnt3a expression.