a method for preparing high molecular weight poly with high performance , including : a ) providing a biogenic guanidine as a catalyst , and a nontoxic acid salt of an essential metal trace element as an activator , and adding the catalyst , the activator , and l - lactide monomer to a polymerization reactor ; b ) evacuating under vacuum and charging the polymerization reactor with nitrogen for three consecutive times to remove air , and allowing the l - lactide monomer to undergo bulk polymerization under vacuum . the bulk polymerization includes a first reaction stage and a second reaction stage , which are separately carried out at different temperatures , pressures , and reaction times .