The Avrarra crystallization kinetic equation fitted by weighted least squaresmethod was investigated and the two weight expressions were derived. If the nonlinearAvrami equation was changed into the linear equation and only the transform ofthe vari-ance of error was considered

then the weight could be expressed asW1=[(1-a)ln(1-a)]2If the transform of the variance of error term arld the feature of DSC measurement wereconsidered simultaneously

then W2=[(1-a)ln(1-a)]2(d2a-dt2/da-dt)2The results calculated from poly(ethylene terephthalate)indicate that the weighted leastsquares methods are better than the general least squares method．