Through combining the genetic polymorphism of CYP1A1-rs1048943, GSTM1, mEH-rs1051740, XRCC1-rs1799782 and XRCC1-rs25489, the methylation of p16 and RASSF1A gene, the length of telomere, smoking status and other factors, the early stage classification model of lung cancer was established by using decision tree and ANN techniques through repeated training. The gene discussed is XRCC1; the disease is lung cancer.