Rotator cuff tear has become one of the diseases affecting people's living quality. Conventional anchor materials such as titanium alloy and poly-lactic acid can lead to postoperative complications like bone defects and aseptic inflammation. Magnesium (Mg)-based implants are biodegradable and biocompatible, with strong potential to be applied in orthopaedics. In this study, we developed a high-purity (HP) Mg suture anchor and studied its mechanical properties and degradation behavior in vitro. Furthermore, we described the use of high-purity Mg to prepare suture anchor for the rotator cuff repair in sheep. The in vitro tests showed that HP Mg suture anchor possess proper degradation behavior and appropriate mechanical property. Animal experiment indicated that HP Mg suture anchor provided reliable anchoring function in 12 weeks and showed no toxic effect on animal organs. In summary, the HP Mg anchor presented in this study had favorable mechanical property and biosecurity. The translational potential of this article: The translational potential of this article is to use high-purity Mg to develop a degradable suture anchor and verify the feasibility of the application in animal model. This study provides a basis for further research on the clinical application of biodegradable high-purity Mg suture anchor.