Objective: To investigate the feasibility and efficiency of three-line relaxation-based group intervention on mental stress management among nursing students. Methods: A total of 224 nursing students were randomly divided into the intervention group in which three-line relaxation training for 12 weeks were delivered together with psychological health education (PHE), and the control group which only delivered PHE. The SelfRating Anxiety Scale (SAS) and the Self Rating Depression Scale (SDS) were used before and after intervention. T-test was used to compare inter-group difference. Results: After 4-week intervention, there’s no significant difference in the score of SAS and SDS between the two groups(P>0.05). After 12-week intervention, average SAS and SDS score of intervention group was significantly decreased compared with before intervention (both P<0.01). After 12-week intervention, no significant changes were observed in the score of SAS and SDS in the control group (both P>0.05). After 4-and 12-week intervention, average score in SAS and SDS of intervention group was significantly lower than that of the control group(P<0.05). Conclusion Three-line relaxation is effective in relieving mental stress of nursing students.