Based on the above theoretical basis and previous studies, further experiments were conducted to explore whether FEN1 mediated DNA damage repair is an important mechanism of gastric cancer resistance to 5-Fu; to research the inhibitory effect of Chinese Medicine Jianpi Yangwei Decoction on FEN1 expression and DNA damage repair; and to determine its efficacy in reversing the resistance of gastric cancer to 5-Fu. This evidence concerns the gene FEN1 and gastric cancer.