Abstract: Objective To explore effect of time-selecting nursing on postoperative mechanical suction of phlegm in lung cancer patients and its influences on blood gas indexes. Methods A total of 102 patients with lung cancer were selected and randomly divided into observation group and control group, with 51 cases in each group. The observation group was treated with mechanical suction of phlegm under time-selecting nursing, while control group was given mechanical suction of phlegm under routine nursing. The clinical effect, clinical indexes, hospitalization time, and changes of arterial blood gas indexes before and after intervention were compared between the two groups. The incidence of complications during hospitalization was recorded in both groups. Results The effective rate of intervention in observation group was 92.16%, which was significantly higher than 76.47% in control group(P<0.05). After intervention, heart rate(HR)and hospitalization time of observation group were significantly better than those of control group(P<0.05). After intervention, while blood oxygen saturation(SpO₂)was significantly higher than that of control group(P<0.05). After intervention, the pH value and arterial oxygen partial pressure ［p(O₂)］ in both groups significantly increased, while arterial carbon dioxide partial pressure ［p(CO₂)］ significantly decreased in both groups, and levels of p(O₂)and p(CO₂)in the observation group were significantly better than those - in the control group(P<0.05). The incidence of postoperative complications in the observation group was 9.80%, which was significantly lower than 31.37% in the control group(P<0.05). Conclusion The implementation of time-selecting nursing for patients with mechanical suction of phlegm after lung cancer surgery can significantly improve the blood gas indexes, and has less postoperative complications.