The invention provides a preparation method of a cotton and ramie fabric with a self-adaptive temperature regulation function. The method comprises the following steps: 1) preparing a prepolymer through ammonia esterification reaction; 2) carrying out a graft copolymerization method on the prepared prepolymer to obtain a graft copolymer. The self-adaptive temperature regulation polymer material prepared by adopting the process has a classic temperature regulation function, and self-adaptive temperature regulation is carried out according to ambient temperature; moreover, the service life is long, the temperature regulation performance is stable, daily operations such as repeated washing can be adapted, phase transition temperature is regulated, and other external supply energy sources are not needed. The method has simple, quick, economical and safe processing procedures, and the using of special equipment is not needed, and therefore, the cost can be reduced, and the production efficiency is improved.