A slippery liquid-infused porous surface (SLIPS) was developed on the AZ31 Mg alloy to provide corrosion protection. A layered double hydroxide (LDH) was applied to providing accommodation for liquid lubricants. The electrolyte pH was adjusted to obtain the best LDH film for the development of a SLIPS. The surface morphology, surface wettability, and electrochemical behavior of the SLIPS formed at different pH values were investigated. The results indicated that the MgAl-LDH film synthesized at a pH of 10.5 had a maximum thickness of 3.51 μm to accommodate the most silicone oil, with a mass of 0.22 mg/mm², which provided the best corrosion protection, with the lowest corrosion current density of 3.72×10^-9 A/cm². On the other hand, compared with the superhydrophobic surface, the SLIPS imparted better corrosion resistance for the AZ31 substrate in both electrochemical behavior and long-term immersion test. The improved corrosion resistance of the SLIPS can further accelerate the application of Mg alloys in practice.