The purpose of this paper is to deal dealing with residual measurement of quenched steel based on neutron diffraction method and its verification by finite element analysis on the stresses induced by phase transformation. The initial interplanar spacing d(0) and elastic constant were measured with rotating specimen method, the residual stress in quenched carbon steel S45C was obtained by means of neutron diffraction. Then a micromechanical approach and simulation based on metal-thermal-mechanical theory were carried out to estimate the microstructure in the steel due to phase transformation during quenching process. Finally the measured results of XRD, neutron diffraction as well as calculated value were compared and discussed.