Cold-sprayed Zn-Al composite coatings can provide good corrosion resistance for magnesium alloys. This experiment employs AZ31B magnesium alloy as the substrate for the deposition of a Zn-Al composite coating.To further improve the performance of cold-sprayed Zn-Al composite coatings， the coatings are subjected to annealing treatment at 200， 250 ℃， and 300 ℃. The microstructure morphology and properties of the cold-sprayed Zn-Al composite coatings before and after heat treatment are analyzed by X-ray diffractometer （XRD），scanning electron microscope （SEM）， microhardness tester， electrochemical workstation，and salt spray corrosion test equipment. The results show that after annealing treatment at different temperatures， the coatings do not undergo oxidation or phase transformation， and the microstructure of the coatings becomes denser and the corrosion resistance improves after annealing treatment. With the increase of annealing temperature， the coatings show the phenomenon of annealing hardening. When the annealing temperature is 250 ℃， the composite coatings are the densest， and the porosity is 0.3998%. Electrochemical and salt spray tests show that the coatings after annealing treatment form a dense corrosion layer， which improves the corrosion resistance of the coatings. When the annealing temperature is 250 ℃， the corrosion resistance of the coatings is the best.