Abstract: The kinetic parameters of grain boundary and precipitate interface in 18 Ni maraging steel were studied by gas chromatograph as hydrogen detctor. The evolution rate peaks of grain boundary and precipitate interface appeared at 378 K and 405 K with 3.00 K min~(-1) heating rate and 0.55mm specimen thickness. The trapactivation energies needed to escape from these sites were obtained from the relationship between peak temperature and heating rate to be 14.2 kJ mol~(-1) and 23.1 kJ mo1~(-1), respectively. The rate constants of hydrogen evolution from these were 3.39 exp (-14.2/RT) min~(-1) and 26.34 exp(-23.1/RT) min~(-1), respectively.