In order to meet the special needs of the environment for the different parts of the same component in the aerospace industry, gradient structural materials have gradually attracted widespread attention from scholars at home and abroad. In this paper, the TA15-Ti2AlNb gradient structure material was prepared by laser solid forming. The microstructure evolution and microhardness of TA15-Ti2AlNb dual alloy materials were studied. The results show that with the increase of Al and Nb content, the transformation of the laser solid formed TA15-Ti2AlNb dual alloy from the TA15 alloy side to the Ti2AlNb-based alloy side phase is α and β phase, α, α2 and β/B2 phases , α2 and β/B2 phases, α2, β/B2 and O phases, and α2 and B2+O phases. And the grain morphology gradually changes from epitaxially grown columnar crystals to isotropic crystals of isotropic growth, and a significant CET transition occurs. The diffusion of elements caused by thermal effect during the deposited process is the main factor for the distribution of elements in the final dilution zone, which ultimately leads to a significant change in the microstructure and phase composition of the deposited samples.