The invention relates to lysine rheinic acid, a method for making same, and the application in treatment of tumor. The method is characterized in that the carboxyl of rheinic acid in the solution and the amino of lysine to form a salt structure to enhance the degree of solubility of rheinic acid in the solution; propanone or absolute alcohol is used to make lysine rheinic acid be separated out in a crystallization form, and the stable lysine rheinic acid crystallization is obtained by separating, purifying and drying; lysine rheinic acid has a appreciable inhibitory action for proliferation and growth of tumour cell, proved by vitro and vivo experiments. The lysine rheinic acid will become an ideal candidate drug for treating tumor.