The compositions and the microstructures of styrene (S)-4-Methacryloyloxy-2.2.6.6-tetramethylpiperine (M) copolymers initiated with free radical have been studied by 250 MHz1H-NMR spectra and M-centred triad distributions were quantitatively measured. It is confirmed from the above results that this copolymerization system belongs to the first order Markov chain model. The corresponding reactivity ratios established are rM=0.32

rs=0.60

respectively. The S-centred triad distrbutions for the copolymers rich in styrene were also quantitatively estimated. The observed S-centred triad fractions agree very well with those calculated theoretically.