BymeansoftheintensitytheoryofX-rayscatteringandthetwo-phaseconceptofhighpolymer,thebasicformulaofthecrystaUinityinblockcopolymershasbeenproposedafterthecorrectionsofatomic,temperature,absorption,Lorentzandpolarizationfactor.Applicationofthismethodtodifferenttypepoly(oxyethylene-styrene)blockcopolymersandthesametypeblockcopolymerswithdifferentEOcontentsindicatesthatthecrystallinityinpoly(oxyethylene-styrene)blockcopolymersincreaseswiththeincreaseoftheEOcontentanddecreasesintheorder:PEO-PS-PEO>PEO-PS>PS-PEO-PS.