Abstract: With the development and progress of neutron science apparatus technology in China, neutron diffraction technology has been widely used in aviation, aerospace, nuclear power, automobile and other fields. In this paper, the principles and related basic knowledge of residual stress measurement by neutron diffraction were introduced. Compared with other deep stress measurement methods, neutron diffraction has high penetration, and it is the most effective nondestructive method to obtain three-dimensional stress in materials and engineering parts, especially suitable for local stress measurement. It has unique advantages in revealing the evolution of residual stress and the related deformation and phase transformation mechanisms during manufacturing or service. The development of corresponding in-situ experiment and testing technology provides an important technical means for material development and performance evaluation. Neutron diffraction technology will play an irreplaceable role in the fields of material and engineering.