Abstract: The energy spectra of β decay and internal conversion electrons of 137Cs are measured by Si( Li) drift detector. The energy spectrum of β decay is studied by Curie plot and the internal conversion coefficients are obtained from the energy spectrum of internal conversion electron. The obtained maximum energy of β decay for 137Cs is ( 513.11±1.76) keV with an error 0.17% with respect to the reference data and the obtained internal conversion coefficients correspond to K/L = 5.712±0.217 and M/L = 0.264±0.018 with the errors 0.92% and 1. 54% with respect to the reference data，respectively. Then the transition levels of β and γ decays for 137Cs and its decayed daughter nucleus are determined. The spins and parities of 137Cs and its daughter nucleus 137Ba are obtained， then the decay scheme of 137Cs is plotted. As a result，it is indicated that the experimental technology is credible， and can be used for experimental teaching and study of nuclear structure as well as it can provide the necessary experimental data for nuclear structure.

Key words: Beta decay, internal conversion electron, Curie plot, internal conversion coefficient, decay scheme