Objective To investigate feedback regulation of close-loop muscle relaxant injection system on accuracy of cisatracurium besilate usage. Methods Two hundred patients undergoing laparoscopic cholecystectomy surgery, aged 20 to 40 years old, at ASA Ⅰ or Ⅱ, were randomly divided into two groups: control group and treatment group (n＝100 each group).In the control group, the patients received injection of cisatracurium besilate with closed-loop muscle relaxant injection system at 1.5–2.0 μg·kg－1·min－1, until 30 min before the end of surgery; if the muscle relaxant level could not meet the requirement of the operation, extra 0.05 mg·kg－1 was added.The treatment group was adopted closed-loop muscle relaxant monitoring under negative feedback regulation of infusion cisatracurium, and the close-loop control parameters were set to: drug was added when TOF was 8%, and injection speed was 2.5 μg·kg－1·min－1, maintaining speed was 0.33 μg·kg－1·min－1, the stimulus current for monitoring muscle relaxant was 60 mA , and the pulse width was 200 μs.The Cooper score, cisatracurium dosage, and muscle recovery index, TOFr75 and TOFr90 of the two groups were compared.Prediction probability (Pk) of NI on awakening period of eye opening and directional force recovery of the two groups were detected, and regression equation was established to predict ED50 and ED95 related NI . Results Cooper score was significantly higher in the treatment group than in the control group (P＜0.01).Muscle recovery index, TOFr75, TOFr90, and cisatracurium dosage per unit time and body mass were significantly lower in the treatment group than in the control group(P＜0.01). Pk of NI on awakening period of eye opening and directional force recovery of the two groups were higher than 0.5; and Pk of the treatment group were significantly higher than those of the control group (P＜0.01). Regression equation predicted that ED95 was significantly lower in the treatment group than in the control group (P＜0.01), while the ED50 between the two groups has no significant difference (P＞0.05). Conclusion The accuracy of closed loop muscle relaxant injection system is higher than that of the traditional method, it provides better muscle relaxation effect for tracheal intubation, reduces recovery time, increases the Pk of NI on patient awakening.