Objective: To investigate the effect of three-dimensional conformal radiotherapy (3D-CRT) combined with PC chemotherapy (paclitaxel + carboplatin) on non-small cell lung cancer (NSCLC) patients and the serum levels of CA125, tissue inhibitor of metalloproteinase-1 (TIMP-1), serum amyloid A (SAA) and T-lymphocyte subsets. Methods: A total of 100 patients with NSCLC treated in Affiliated Hospital of Guangdong Medical University from May 2015 to December 2017 were selected as the study subjects. They were divided into control group and observation group according to random number table method, with 50 cases in each group. The observation group was treated with 3D-CRT combined with PC chemotherapy, while the control group was treated with PC chemotherapy. The two groups were treated for 4 cycles. The therapeutic effect, serum CA125, TIMP-1, SAA, T-lymphocyte subsets and adverse reactions were compared between the two groups. Results: Four cases were lost to follow-up both in the two groups. The overall response rate in the observation group (43.48%, 20/46) was higher than that in the control group (23.91%, 11/46; χ²=3.941, P=0.047). The serum levels of CA125, TIMP-1 and SAA of the two groups had no significant difference before treatment, and the levels of these indexes decreased after treatment. The serum levels of CA125, TIMP-1 and SAA in the observation group after treatment were (12.31±1.13) U/ml, (275.31±13.69) pg/ml and (47.21±7.21) mg/L, which were lower than those in the control group [(30.36±1.98) U/ml, (320.36±17.23) pg/ml, (65.92±8.36) mg/L], with significant differences (t=53.699, P<0.001; t=13.884, P<0.001; t=11.495, P<0.001). The levels of CD3⁺ , CD4⁺ , CD8⁺ and CD4⁺ /CD8⁺ of the two groups had no significant difference before treatment, and the levels of these indexes decreased after treatment. The levels of CD3⁺ , CD4⁺ , CD8⁺ and CD4⁺ /CD8⁺ in the observation group were (35.27±10.31)%, (20.27±6.72)%, (15.89±3.37)% and 0.91±0.37, which were higher than those in the control group [(30.77±9.27)%, (15.27±5.73)%, (12.02±2.69)% and 0.75±0.39], with significant differences (t=2.201, P=0.030; t=3.840, P<0.001; t=6.087, P<0.001; t=2.019, P=0.047). There were no significant differences in the adverse reactions such as nausea and vomiting [63.04% (29/46) vs. 43.48% (20/46); χ²=3.537, P=0.060], phlebitis [6.52% (3/46) vs. 4.35% (2/46); χ²=0.000, P>0.999], abnormal liver function [6.52% (3/46) vs. 2.17% (1/46); χ²=0.261, P=0.609] and myelosuppression [8.70% (4/46) vs. 6.52% (3/46); χ²=0.000, P>0.999] between the observation group and the control group. Conclusion For patients with NSCLC, 3D-CRT combined with PC chemotherapy can improve the overall response rate, decrease the levels of serum CA125, TIMP-1 and SAA, and improve the immune function of patients. The therapeutic effect is remarkable and the safety is good. The therapeutic scheme is suitable for the treatment of NSCLC.