Magnesium alloys, as the lightest commercial metal engineering structural materials, have good application prospects in the automotive, communication equipment, aerospace, and military industries because of their light specific gravity, high strength properties such as specific strength and stiffness, shielding from electromagnetic radiation, and easy recycling. In this paper, starting from the density and microstructure of magnesium alloy, the mechanical properties and corrosion resistance of magnesium alloy are proposed to measure the indexes, and the corresponding prediction model is constructed. Then, fine-crystal magnesium alloys are prepared sequentially by ingot casting and isometric channel extrusion, and then the microstructure of magnesium alloys is observed by scanning electron microscope and transmission electron microscope to extract the micro-parameters of magnesium alloys. A martensitic phase transition topology model was introduced to determine the macroscopic shape strain of magnesium alloy crystals. Complex network analysis is used to quantify the topological structure parameters of a magnesium alloy network in terms of degree, clustering coefficient, and average path length. Finally, the correlation between the macroscopic features and microstructure of magnesium alloy is explored with the obtained data, and the mechanical and corrosion resistance properties of magnesium alloy are analyzed through simulation experiments by combining them with the constructed prediction model. The microstructural topological characteristic parameters of magnesium alloys show that when the pressure is 50 kPa, the average path length after weighting decreases from 36.012 × 10−3 to 34.015 × 10–3, and the force transfer efficiency is gradually increasing. The AZ31 alloy samples obtained from casting in this paper have a capacitive arc diameter of about 1600 Ω-cm² and the best corrosion resistance among the tested samples.