AbstractThe stereosequence of polylactide has been analyzed with 13C‐NMR spectroscopy, according to which syndiotactic addition is preferred. According to Markovian statistics, the reactivity ratio, which determines the extent of the syndiotactic stereosequence in the polymer chain, can be calculated by an analysis of the carbonyl and methine regions in the spectra. Moreover, the average lengths of segments SS and RR can be proposed and calculated with the distributing function of the sequence. On this basis, we have investigated the formation mechanism with respect to the preference for the syndiotactic addition of polylactide chains. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010