The invention relates to an application of mud snail polypeptide in lung cancer resistance, and especially relates to an application of the mud snail polypeptide in an anti-lung cancer H1299 cell drug. The mud snail polypeptide components are respectively obtained by obtaining a mud snail polypeptide crude extract through enzymolysis method with trypsin and then performing separation and purification through ultra-filtration, gel column separation method and reversed-phase high-performance liquid chromatography technology and the like. The separated components are respectively subjected to research on proliferation inhibition on lung cancer H1299 cell, wherein the research result proves that all the components can significantly inhibit the proliferation of the lung cancer H1299 cell with the proliferation inhibition index on the H1299 cell being more than 44.6%. The application is low in raw material cost and is simple and mild in extraction conditions. The extracted mud snail polypeptide has significant inhibition effect on proliferation of the lung cancer H1299 cell and provides a theoretic basis in development of the anti-lung cancer drugs with the mud snail polypeptide as a raw material.