A convenient method for the synthesis of poly(butylene succinate) (1) of high molecular weight has been developed. This polyester was prepared readily by the distannoxane-catalyzed polycondensation of succinic acid (2) with 1,4-butanediol (3) in decalin at 190 degrees C under azeotropic condition. The polycondensation proceeded in decalin-melted polymer two-phase, giving 1 with the number average molecular weight of 150000.