A polyesterification method comprises steps of mixing, by combining N,N-dialkylformamide dialkyl acetal with a tin catalyst, so as to transfer an alkoxy group from the N,N-dialkylformamide dialkyl acetal to the tin catalyst to obtain a Sn coordination complex; and polymerization, by conducting a ring-opening polymerization of a ester under the catalysis of the Sn coordination complex, and finally to obtain a polyester compound; wherein, the chemical formula of the N,N-dialkylformamide dialkyl acetal is (RO)2CHNR2, with the R being an alkyl group.