Abstract: KRAS gene belongs to Ras gene family.Its coding protein controls cell proliferation, differentiation and apoptosis by activating downstream signaling pathways.Once KRAS gene mutates, KRAS proteins could be overexpressed and continuously activated, which in turn overactivates downstream signaling pathways, leading to uncontrollable cell proliferation and malignancy, and ultimately tissue canceration.Exploring therapeutic strategies for tumors related to KRAS mutations has always been one of the research hot spots.However, KRAS protein mutants have been recognized as one of the difficult kinds of target proteins.The design of small molecule inhibitors directly targeting KRAS protein mutants is very challenging, and there are no related drugs approved for marketing.Here, we briefly summarize the structure and function, related signaling pathways, role of mutants of KRAS in tumorigenesis and the developments of small molecule inhibitors of KRAS mutations, aiming to provide new ideas for the treatment of KRAS mutant cancers.