This study aimed to examine the effect of progressive muscle relaxation therapy (PMRT) on cortisol level, the Stress Arousal Checklist (SACL) score, blood pressure, and heart rate in colorectal cancer patients undergoing laparoscopic surgery. Forty-six patients were divided into control and experimental groups. Cortisol levels, blood pressure, and heart rate were measured before surgery and between 8:00 and 11:00 a.m. on the first, third, and fifth days after surgery. SACL score was measured before surgery and on the fifth day after surgery at the same time points. PMRT was performed twice a day for 5 days. Analyses of covariance with advanced covariate levels and t tests showed that PMRT helps colorectal cancer patients achieve a lower stress response and provides an important basis for stress control.