The invention discloses a building method of a library for detecting non-small cell lung cancer gene mutation and a kit. The method includes: using tubular reaction to complete genome DNA breaking and connector connection, performing hybrid capture on connection products after amplification and non-small cell lung cancer related gene target area probes, and performing BGISEQ-500 / 1000 platform sequencing and data analysis to obtain mutation conditions. The method has the advantages that the experiment flow is optimized greatly by the tubular reaction, operation complexity and time are reduced, and the requirements on clinical sample initial amount are lowered; multiple genes and multiple sites can be detected in one step, point mutation, insertion and deletion, structural variation and copy number variation are covered, the detecting result is accurate and overcomes the defect that a PCR capture method cannot detect the structural variation in one step, and the effectiveness of the high-throughput sequencing applied to the detection of the non-small cell lung cancer gene mutation; the method is wide in coverage, high in cost performance, capable of providing a reference basis for the diagnosing, treatment and drug use performed by doctors, and the method is suitable for being popularized and used in a large-scale manner.