This paper reports the IR spectroscopy of CPE synthetized by solid-phase chlorination pro-cess under different conditions．We also emphat ically discussed the structural characterics of CPE，chlorineted by two steps．It was observed that the modification of a characterizistic crys-talline structure and chlorine distribution on-(CH2)n-chain segments．The results showed that the solid-phase chlorination mainly occured in amorphous regions under the lower temperature conditions，and also formed a block structure with a high and low (or non-) chlorinated chain segment in CPE．If the solid-phase chlorination was processed in two steps，the crystalline re- gion would be destroyed with a higher degree．The chlorination process is limited any longer the amophous region，and whether the destruction of crystalline structure is related to the degree of chlorination in the second step．Even if its chlorine contents is all the same as to CPE．But only variation with chlorination degree in two steps，therefore the structure will be signif-cantly different．