In view of the low coupling efficiency and long simulation time of vertical couplers, an inverse design simulation platform of multi-layer heterostructures is built. With the help of the function-oriented idea of the inverse design and the advantages of high-performance computing, micro/nano-photonic devices with complex multi-layer heterostructures can be generated automatically by convex optimization algorithms after the initial structures are built and the target functions are set. A high-performance vertical coupler based on this inverse design simulation platform is proposed in this paper. The coupling efficiency improves greatly after an Al mirror is integrated into the coupler. The simulation results show that the coupling efficiency of the coupler is 88.42% at 1550 nm wavelength (coupling efficiency is 32.45% without an Al mirror), and the coupler has a 3 dB bandwidth of 103 nm (1500--1603 nm) with good bandwidth and low loss characteristics.