In this article the chain structure of PEMA was studied by 1H-NMR

13C-NMR and COSY spectroscopy. Some difficulties in recognition of the spectra of PEMA come from the overlap of proton peaks. The assignment of the peaks in spectra of PEMA was discussed deeply with information provided from H-H COSY and C-H COSY spectra. But there are still some problems about the assignment of 13C peaks of β-CH2 in tetrad level. Finally the pentad sequences of atactic PEMA were calculated based on the discussion mentioned above.