Ti-Ti3Al metal composite prepared by in-situ synthesis is a good method to improve the properties of titanium matrix composites. In this paper, the influence of Al content on the microstructure and mechanical properties of in-situ synthesis Ti-Ti3Al metal composite produced by selective laser melting （SLM） was studied. The forming test of Ti-AlSi10Mg composite powder with different mixing ratios was carried out by SLM technology and in-situ synthesis technology, and the phase, microstructure, microhardness, wear performance, tensile and compression properties were analyzed. The results show that Al enters into Ti crystal during the forming process, forming Ti-Al substitution solid solution, which strengthens the solid solution of the sample and precipitates Ti3Al particle reinforced phases. With the increase of Al content, the mechanical properties of the sample gradually improved. The microhardness was significantly increased. When Al mass fraction was 10%, the hardness increased to 538.56 HV, reaching more than twice that of pure titanium (220.59 HV). The wear performance increases and the average friction coefficient of the sample decreases gradually. The maximum compressive strength reaches 1 653.9 MPa, which is 164.48% higher than the pure titanium sample, and better than the pure titanium plate after annealing (400-450 MPa) and the TC4 alloy formed by SLM (1 128 MPa). The tensile strength firstly increased and then decreased with the increase of Al, but it was still higher than the pure titanium sample. The combination of in-situ synthesis and SLM technology is of great significance to improve the properties of composite materials.