Aluminum alloy die casting die currently has a problem that the surface is easy to generate pitting, wear,poor knockout performance. In order to solve this problem, the Al2 O3 -TiO2 ceramic coating on mould H13 by plasma spraying was prepared. We have designed orthogonal experiment based on current, voltage and spraying distance and optimized spraying parameters. The results show that by surface strengthening with the optimized process, the hardness of Al2 O3 -TiO2 coating is 976. 1HV, the friction factor is about 0. 4. The coating wear hardness, wear resistance and knockout perfomance are improved significantly.