The aim of this paper is to get the curve of log[n]--logM of the sample tested，in the absence of a linear polymer of sample of same chemical composition based on universal calibration．The linear seetion of the curve is extended in the direction of increasing molecular weight．The [n]L values of unbranched and branched toolecule of same MW are determined by the points on lines，and／or for linear GPC’s columns，the linear section of log [n]-V might be extended in the direction of decreasing elu-tion volume．The poInts on extended lines might determ

ine [n]L value of the linear and branched sample of same elution volume．Thus， ([n]b/[n]L)M=G or ([n]b／[n]L)Ve一G，is obtained．The experiments proved that the branching has an effect on M[n]，i．e．Mb[n]b= ML[n]L．Correction must be made．After correction such as Mb[n]b=ML[n]L2一G)，the [n]b and Mw values calculated from th e data obtained via GPC coupled with an automatic viseometer agreed well with corresponding values measured by classical viscometry and light scattering method．