Objective To analyze the efficacy of icotinib in combination with pemetrexed in the treatment of epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC).Methods A total of 152 patients with advanced NSCLC admitted to our hospital from January 2018 to July 2021 were selected and divided into the control group and the experimental group by the random number table method, with 76 cases in each group. The control group received icotinib orally, 125 mg each time and three times a day. The experimental group received pemetrexed at a dose of 500 mg/m² intravenously every three weeks on the basis of icotinib treatment. The therapies were maintained in both groups until disease progression or drug intolerance. The anti-tumor efficacy, levels of tumor markers, lung function, liver function, immune function and drug safety were compared between the two groups after three courses of treatment, and the 1-year survival of the two groups was analyzed.Results A total of three cases were lost to follow-up during the treatment. The disease control rate of the experimental group was higher than that of the control group (P < 0.05). The differences of levels of thymidine kinase, neuron-specific enolase, and carcinoembryonic antigen, forced vital capacity, forced expiratory volume in one second/forced vital capacity, Th1/Th2, Th17/Treg, and CD4⁺/CD8⁺ before and after the treatment in the experimental group were higher than those in the control group (P < 0.05). The differences of levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL) before and after the treatment were not different between the two groups (P > 0.05). The overall incidence of adverse drug reactions in the experimental group and the control group were 25.33% and 21.62%, with no significance difference between the two groups (P > 0.05). Two cases in each group were lost to follow-up at the end of the observation, when 59 of 73 patients in the experimental group and 56 of 72 patients in the control group eventually survived. There was no significant difference in the 1-year overall survival curve between the two groups (P > 0.05).Conclusions Icotinib combined with pemetrexed enhances short-term anti-tumor efficacy, inhibits the synthesis of tumor markers, and improves lung function and immune function safely in the treatment of EGFR-mutated NSCLC.