With the technology of IR spectrum and crystal morphology,studying the effect on interatomic bonding action and molecular shape of coagulating agent PASC when it is prepared by various methods.It shows that as PASC is produced by basifying polymerization,comparing to that by others way,the IR spectrum of PASC shows,965cm -1 peak proportion reflecting Si O Al bond accrete 118%,266%,875cm -1 peak proportion reflecting Al O Al bond accrete 23%,30%.It may be caused by multinuclear hydroxy aluminum’s content and Zeta electric potential increases in the process hydrolyze concrete with PASC.It disappear in crystal morphology,molecular chain is longer and branching further,so that PASC have better potentiality of arching and charge neutralization.