Abstract: Objective To observe effect of risk warning management in pregnant women with late threatened abortion by magnesium sulfate treatment. Methods A total of 22 pregnant women with late threatened abortion by treatment of magnesium sulfate from January to December 2019 were selected as observation group, and they were conducted with whole process risk warning management. Another 25 pregnant women without risk warning management before 2019 were selected as control group. The mastery degree of risk warning management indicators(score for mastery of drug knowledge, score for standard manipulations of magnesium sulfate and infusion pump, score for quality control inspection of high-risk drug management)of nurses in charge of pregnant women in both groups were compared. The satisfaction degree of pregnant women to nursing services, scores of Self-rating Anxiety Scale(SAS)and Self-rating Depression Scale(SDS), and nursing risk events were compared between the two groups. Results Score for mastery of drug knowledge, score for standard manipulations of magnesium sulfate and infusion pump, and score for quality control inspection of high-risk drug management of nurses in charge of pregnant women in the observation group were significantly higher than those in the control group(P<0.05). The satisfaction degree of pregnant women in the observation group was 90.91%(20/22), which was significantly higher than 64.00%(16/25)in the control group(P<0.05). The scores of SAS and SDS in the observation group were significantly lower than those in the control group(P<0.05). The incidence of nursing risk events in the observation group was significantly lower than that in the control group(P<0.05). Conclusion Risk warning management can effectively reduce the incidence of nursing risk events, enhance the risk awareness and prevention ability of nursing staffs, increase the satisfaction degree of pregnant women, and ensure safety of pregnant women.