Abstract：Objective：To study the effect of nursing based on constitution differentiation of Chinese medicine on patients with gestational diabetes mellitus on the basis of protection motivation theory. Methods：A total of 96 cases of patients with gestational diabetes mellitus were divided into the observation group and the control group according to random number table，48 cases in each group. The control group was given routine nursing；based on the nursing of the control group，the observation group was additionally given nursing based on constitution differentiation of Chinese medicine on the basis of protection motivation theory. The ability of self- nursing， self- efficacy， and the level of blood glucose were compared between the two groups. Results：Before intervention，when compared the scores of self-nursing ability in each dimension and the total scores between the two groups，there was no significance in the difference(P＞0.05). After intervention，the scores of self-nursing ability in each dimension and the total scores in the two groups were increased when compared with those before intervention，and each score and the total score in the observation group were higher than those in the control group(P＜0.05). Before intervention， when compared the score of self- efficacy between the two groups， there was no significance in the difference(P＞0.05). After intervention，the score of self-efficacy in the two groups were increased when compared with those before intervention，and the score in the observation group was higher than that in the control group (P＜0.05). Before intervention， when compared the levels of fasting blood glucose and postprandial 2 h blood glucose between the two groups，there was no significance in the difference(P＞0.05). After intervention，the levels of fasting blood glucose and postprandial 2h blood glucose in the two groups were improved when compared with those before intervention， and the levels in the observation group were better than those in the control group(P＜0.05). Conclusion： On the basis of protection motivation theory，the nursing based on constitution differentiation of Chinese medicine can effectively control the level of blood glucose of patients，improve their self-nursing ability and the level of self-efficacy.