The work aims to promote the modified reaction between Al/NiCr composite coatings and prepare a Ni-Al intermetallic compound protective coating with certain oxidation resistance through in-situ reaction. The Al/NiCr composite coatings were deposited on the surface of pure Ti substrate by arc spray technology and plasma spray technology, the sprayed Al/NiCr/Ti specimen was then heated in the furnace at 700 ℃, and the microstructure of the coatings before and after heat modification treatment and the formation mechanism of Ni-Al intermetallic compounds were studied. In addition, the oxidation tests of the Al/NiCr/Ti specimen (after heating and polishing treatment) and the uncoated Ti were conducted at 800 ℃ for 100 hours. By modifying Al/NiCr spray coatings on Ti substrate through furnace heating treatment at 700 ℃, Ni2Al3 and NiAl intermetallic compounds with certain Cr elements were formed through in-situ reaction between Al/NiCr composite coatings. In addition, the mixture organizations of Al liquid and Cr2O3 and NiO were dispersed in the entire Al and NiCr diffusion reaction zone. However, the generated Ni2Al3 intermetallic compound melted, and only the NiAl intermetallic compound with high melting point could exist stably. The NiAl intermetallic compound layer obtained by the modification reaction has a good high temperature protection effect on the Ti substrate.