This work successfully prepared LiAl LDHs coatings on AZ31 Mg alloy under standard atmospheric pressure and low temperature. The whole process did not require a hydrothermal autoclave reactor and high pressure. Electrochemical test results showed that the coating was able to provide good corrosion protection performance. The LiAl LDHs coatings provided a large low-frequency impedance on AZ31. When the treatment time was 24 h, the maximum |Z|0.01Hz at pH = 12 was 5.14 × 104 Ω∙cm2, which is more than an order of magnitude higher than the |Z|0.01Hz of 1.81 × 103 Ω∙cm2 for the bare sample. Under the same treatment conditions, the potentiodynamic polarization test results showed that the LiAl LDHs coated samples had a lower corrosion current density and a higher breakdown potential. The icorr was 1.78 × 10−7 A/cm2 and Ebr was −0.82 VSCE compared to the Mg substrate (icorr of 1.13 × 10−5 A/cm2 and Ebr of −1.53 VSCE). Additionally, LiAl LDHs coatings also had a significant inhibitory effect on cathodic hydrogen evolution, providing targeted protection to the cathodic areas.