The work aims to study effects of Mg3Sb2 on structure, corrosion resistance and hardness of Al-Mg3Sb2 multi-phase coatings, and compare properties differences between pure Al coating and those with different contents of Mg3Sb2. The Al-Mg3Sb2 multi-phase coatings with different compositions were prepared on the surface of AZ31B magnesium alloy by using oxy acetylene flame spraying and homemade Mg3Sb2 powder. Microstructure of the coatings was observed by using SEM; phase composition of ball milling powder and coatings was analyzed by using XRD; electrochemical corrosion performance test was performed to the samples in 3.5% NaCl solution through electrochemical workstation (CHI660e); and hardness of the coatings was tested by microhardness tester. The Al-Mg3Sb2 multi-phase coatings with different composition were obtained after flame spraying. The coatings had dense structure, and were subject to a few structural defects including pores and cracks when mass fraction of Mg3Sb2 was 40% and 60%, respectively. The phases in the coatings were mainly Al and Mg3Sb2. Tafel polarization curve test showed that corrosion potential of the coatings gradually shifted positively with the increase of second phase Mg3Sb2. As the mass fraction of Mg3Sb2 reached 80%, the corrosion potential was ?0.9819 V, which was 417.3 mV higher than that of pure Al coating, and corrosion current density of the coatings was 0.048×10?3 A/cm2, which was approximately 1/2 of that of the pure Al coating. Microhardness test showed that hardness of the coatings gradually increased with the increase of Mg3Sb2 content. When the content of Mg3Sb2 was 80%, the average hardness of the coatings reached 334.2HV, which was 6.79 times of that of the pure Al coating. The addition of Mg3Sb2 can contribute to better coatings. The corrosion resistance and microhardness of the coatings gradually increase with the increase of Mg3Sb2 content.