Magnesium (Mg) and its alloys as potential biomaterials have been widely investigated due to their remarkable biodegradability and bioresorbability. However, uncontrollable degradation and the discrepancy between in vitro and in vivo tests demand a much better understanding for their degradation mechanism. In this work, several typical organic components, L-ascorbic acid, L-glutamine, L-alanyl-L-glutamine, and Fetal bovina serum were chosen to elucidate the effects of organic components on the degradation process of pure Mg. The samples were incubated under cell culture conditions for different immersion times. Hank’s balanced salt solution without calcium and magnesium (HBSS) was used as degradation medium. 50 mg/L L-ascorbic acid, 292 mg/L L-glutamine, 862 mg/L L-alanyl-L-glutamine and 10% fetal bovina serum were added, respectively. The influences on the surrounding environment and the degradation products formed were analyzed. The results revealed that the organic components slightly inhibited the degradation during a relative short immersion time, while the degradation rate increased after 14 days of exposure. The reason for this phenomenon was related to the degradation layer, which was composed of a white precipitates layer on the top of the specimen and an inner degradation layer. The addition of organic components favored the precipitation of nesquehonite on the top layer rather than hydromagnesite. In addition, the presence of organic components accelerated the formation of phosphate in the inner degradation layer during the initial immersion, which is mainly composed of carbonate, phosphate and magnesium hydroxide.