In recent years, magnesium (Mg) alloys have attracted great attention due to superior biocompatibility, biodegradability, and other characteristics important for use in biodegradable implants. However, the development of Mg alloys for clinical application continues to be hindered by high corrosion rates and localized corrosion modes, both of which are detrimental to the mechanical integrity of a load-bearing temporary implant. To overcome these challenges, technologies have been developed to improve the corrosion resistance of Mg alloys, among which surface treatment is the most common way to enhance not only the corrosion resistance, but also the bioactivity of biodegradable Mg alloys. Nevertheless, surface treatments are unable to fundamentally solve the problems of fast corrosion rate and localized corrosion. Therefore, it is of great importance to alter and improve the intrinsic corrosion behavior of Mg alloys for biomedical applications. To show the significance of the intrinsic corrosion resistance of biodegradable Mg alloys and attract much attention on this issue, this article presents a review of the improvements made to enhance intrinsic corrosion resistance of Mg alloys in recent years through the design and preparation of the Mg alloys, including purifying, alloying, grain refinement, and heat treatment techniques. The influence of long-period stacking-ordered structure on corrosion behavior of the biodegradable Mg alloys is also discussed.