A method for preparing a pyruvate ester is disclosed. In the method of the present invention, a lactate ester is oxidized by hydrogen peroxide in the presence of a Ti—Si molecular sieve catalyst. In the present invention, the Ti—Si molecular sieve catalyst is easily filtered and recycled, the reaction conditions are mild due to the usage of hydrogen peroxide, the process is simple and easily performed, the conversion rate of the lactate ester is high, and the selectivity of the pyruvate ester is high.