Objective To analyze the relationship among therapy-related symptoms, quality of life and Karnofsky performance score in lung cancer patients, so as to provide reference for cancer symptom management. Methods A total of 302 lung cancer patients were investigated using the Therapy-related Symptom Checklist (TRSC), the Karnofsky performance score and the Functional Assessment of Cancer Therapy-Lung (FACT-L). Results The total TRSC score among the participants was （20.62±9.10）, quality of life was (91.17±16.08), and Karnofsky performance score was （76.32±13.84）. The intensity of 6 therapy-induced symptoms (loss of appetite, hair loss, nausea, vomiting, feeling sluggish, taste change) were self-rated as "serious or very serious" by more than 20% patients. Pearson correlation analysis indicated that, the correlation coefficient r between the total TRSC score and the total FACT-L score, its subscale score of physical status, social/family status, emotional status, functional status, lung cancer additional attention, and the Karnofsky performance score was -0.617,-0.183,-0.379,-0.194,-0.584,-0.516,-0.374 (P＜0.01 for all). Conclusion Lung cancer patients suffer from serious treatment-induced symptom distress, especially therapy-related loss of appetite, hair loss, nausea, vomiting, feeling sluggish and taste change, and the patients experienced serious therapy-related symptom distress are prone to suffer from worse quality of life and functional status.