The invention discloses a detection method and an application of lung cancer genes. According to the application, the detection method comprises the following steps: constructing a cfDNA library, and conducting hybrid capturing on the cfDNA library by virtue of 12659 probes which are designed in accordance with 105 lung cancer associated genes, sequencing the genes by virtue of a computer, and conducting data analysis on a sequencing result, so that comprehensive and accurate lung cancer gene information is obtained. According to the application, the detection method can implement with a small amount of peripheral blood, so that noninvasive detection is actually achieved. The detection method disclosed by the invention, by capturing, sequencing and analyzing important lung cancer genes in ctDNA, can be used for screening lung cancer in the early stage; therefore, related medication gene mutation information is provided for patients with the lung cancer, and an important reference is provided for the early diagnosis of the lung cancer, personalized accurate medication guidance, effectiveness evaluation and prognosis dynamic monitoring.