Preparation of cyclic esters ring-opening polymerization catalyst phosphoric acid creatinine guanidine

The invention relates to a process for preparing cyclic ester ring-opening polymerization catalyst, namely phosphoric acid creatinine guanidine which is used to prepare non-toxic, metal-free, and bionic organic guanidine compound. The invention adopts a direct synthesis method without catalyst, utilizing creatinine and phosphoric acid as) raw material, utilizing water to be dissolvent, dripping phosphoric acid water solution into a reactor containing creatinine, and molar ratio of creatinine and phosphoric acid is 1:1-1:2, heating-up after dripping, reacting in 20-40 DEG C, cooling to indoor temperature after reacting, reducing pressure and steaming in rotation to remove dissolvent, drying the solid body in normal temperature and vacuum, and finally getting milky phosphoric acid creatinine guanidine to be final products and finally getting the final products, namely the milky creatinine guanidine. The invention is characterized in that firstly, the invention adopts a direct synthesis method without catalyst a