An advanced method of producing AlN-Al3Ti/ZL101 in-situ composite is described in this paper. The microstructure of the in-situ composite is studied by the analyzing method of OM, SEM and TEM and the mechanical properties of the composite are also tested. The results show that the size of reinforcing phase Al3Ti in the composite is about 0. 5 u,m, which is distributed a-Al matrix uniformly. The size of reinforcing phase A1N is about 30 nm, which distribute inside of eutectic Si. The phase of Al3Ti has the same orientation relationship with a-Al and the phase of A1N has the same orientation relationship with eutectic Si. The tensile strength of AlN-Al3Ti/ZL101 in-situ composite is 369 MPa and it is higher than that of ZL101 matrix.