Microchannel reactors can be considered for biodiesel production because of their high yield, while the efficient premixing of reactants is crucial to get high reaction rates. Based on synergetic strengthening, a novel micromixer including seven inlets in enter section and inner devices of triangular baffle combined with circular blocks in mixing section were designed, the mixing performance and pressure drop of the micromixer were simulated numerically，and the influences of inlet angle, triangular baffle height and circular block diameter on the mixing intensity, mixing pressure drop were investigated. The optimized micromixer structure were proposed with 30°inlet angle , 120 μm triangular baffle height, 120 μm circular block diameter and 330 μm space between the inner devices. The results reveal that the multi-inlets followed by combined inner devices micromixer possess synergetic strengthening effect on mixing, enhances the mixing intensity effectively at least high to 0.9 at Reynolds number Re=1 within 6 mm length and improves the operational flexibility.