Abstract: Because of the high penetrability of neutron beam in general metallic materials, neutron diffraction may easily acquire the three-dimensional information of polycrystalline diffraction from a well-defined gauge volume in any internal position of a structural material specimen or a machine component and then precisely evaluate the strain/stress distribution. The essential theory of angle dispersive neutron diffraction stress measurement technique based on a nuclear reactor was introduced, followed with several typical research examples including the work hardening evaluation of a cold press formed automobile component, the residual stain evaluation of a multilayered steel plate after uniaxial tensile deformation and the stress distribution of steel bar in a steel bar enforced concrete structural component under loading, showing that the angle dispersive neutron diffraction technique has been widely applied to the quantitative evaluations on internal stresses of engineering components and advanced materials in the developed countries. The rapid development and broad application of this strain/stress measurement technique have been highly expected in china.