Abstract: Objective To investigate the effect of ultrasound-guided posterior rectus sheath and transverse abdominis block in patients with open colorectal cancer and its effect on stress response. Methods Eighty-two patients with open colorectal cancer were enrolled between January 2017 and June 2018. They were divided into control group and observation group with 41 cases in each group. The control group was given general anesthesia. On the basis of which, the observation group was given the ultrasound-guided posterior rectus abdominis and the transverse abdominis block. The anesthesia effect was evaluated after the operation. The number of analgesic pump presses, the total dose of sufentanil, the time of anal exhaust, and the time of getting out of bed were counted. Serum cortisol (CORT) and catecholamine (CA) were obtained by enzyme-linked immunosorbent assay (ELISA). Plasma glutamate (GLU) levels, the incidence of nausea and vomiting, hepatic contusion, spleen contusion, puncture infection, chills and bradycardia in the two groups were counted and recorded, comparing the effects of anesthesia and stress on the two groups. Results The number of analgesic pump presses, the total dose of sufentanil, the time of anal exhaust, and the time of getting out of bed were all less (shorter) than the control group (all P<0.05); the observation group and the control group T1, T2 The levels of CORT, CA and GLU were higher than the T0 time point (all P<0.05). The levels of CORT, CA and GLU in the observation group at T1 and T2 were lower than those in the control group (all P<0.05). There was no significant difference in the incidence of nausea and vomiting, headache, dizziness, puncture infection, chills and bradycardia after anesthesia (all P>0.05). Conclusion Ultrasound-guided posterior rectus sheath combined with transverse abdominis block can shorten the symptom improvement time and reduce the dose and stress response of sufentanil in patients with open colorectal cancer. It is worth promoting.