Objective:To compare the effects of pressure controlled ventilation (PCV) and volume controlled ventilation (VCV) on respiratory mechanics, hemodynamics and biochemical metabolism in patients undergoing laparoscopic colorectal cancer surgery.Methods:The clinical data of 78 patients underwent laparoscopic colorectal cancer surgery from August 2019 to June 2020 in Inner Mongolia People′s Hospital were retrospectively analyzed. Among them, 39 patients were treated with PCV (PCV group), and 39 were treated with VCV (VCV group). The respiratory mechanics, hemodynamics and biochemical metabolism indexes 10 min after anesthesia induction (T 1), 10 min after pneumoperitoneum + low head and foot height (T 2), 60 min after pneumoperitoneum + low head and foot height (T 3) and 120 min after pneumoperitoneum + low head and foot height (T 4) were recorded. The respiratory mechanical indexes included mean airway pressure (P mean), airway peak pressure (P peak), pressure of end tidal carbon dioxide (P ETCO 2) and dynamic lung compliance (C Ldyn); hemodynamic indexes included mean arterial pressure (MAP) and heart rate; and biochemical metabolic indexes included base excess, serum natrium, serum potassium, negative logarithm of the hydrogen ion concentration (pH) and blood glucose. Results:The P mean, P peak and P ETCO 2 T 1 to T 4 in PCV group were significantly lower than those in VCV group, P mean: (7.12 ± 1.37) cmH 2O (1 cmH 2O = 0.098 kPa) vs. (8.54 ± 1.84) cmH 2O, (9.80 ± 2.26) cmH 2O vs. (11.63 ± 2.87) cmH 2O, (9.51 ± 2.17) cmH 2O vs. (11.72 ± 2.90) cmH 2O, (7.04 ± 1.34) cmH 2O vs. (8.65 ± 1.88) cmH 2O; P peak: (13.41 ± 2.68) cmH 2O vs. (15.06 ± 3.05) cmH 2O, (20.92 ± 3.11) cmH 2O vs. (23.45 ± 4.02) cmH 2O, (21.14 ± 3.50) cmH 2O vs. (23.69 ± 4.26) cmH 2O, (15.03 ± 2.74) cmH 2O vs. (16.45 ± 3.21) cmH 2O; P ETCO 2: (30.59 ± 1.57) mmHg (1 mmHg = 0.133 kPa) vs. (32.04 ± 2.11) mmHg, (35.02 ± 4.15) mmHg vs. (39.88 ± 4.76) mmHg, (35.90 ± 4.22) mmHg vs. (40.11 ± 4.87) mmHg, (34.33 ± 4.17) mmHg vs. (37.65 ± 2.69) mmHg; the C Ldyn was significantly higher than that in VCV group: (40.68 ± 3.98) ml/cmH 2O vs. (35.47 ± 2.56) ml/cmH 2O, (30.25 ± 3.21) ml/cmH 2O vs. (22.40 ± 2.75) ml/cmH 2O, (29.78 ± 3.06) ml/cmH 2O vs. (22.60 ± 2.81) ml/cmH 2O, (40.32 ± 4.25) ml/cmH 2O vs. (33.61 ± 2.81) ml/cmH 2O, and there were statistical differences ( P<0.01 or <0.05). The MAP and heart rate T 1 to T 4 in PCV group were significantly lower than those in VCV group, and there was statistical difference ( P<0.01 or <0.05). The base excess, serum natrium, serum potassium and pH T 1 to T 4 in PCV group were significantly higher than those in VCV group, while the blood glucose was significantly lower than that in VCV group, and there was statistical difference ( P<0.01 or <0.05). Conclusions:Compared with VCV, PCV can promote the recovery of respiratory mechanics index, stabilize hemodynamics and improve biochemical metabolism index in patients undergoing laparoscopic colorectal cancer surgery.