An embedded strain measurement method based on fiber bragg grating sensor was proposed to solve difficult problems in measuring the internal strain response of solid rocket motor grain. The solid rocket motor tester of embedded fiber bragg grating strain sensor was designed, and the cold pressurization test was carried out on the tester. The axial and circumferential strains in the grain structure were obtained under cold pressurization test. Research shows that the proposed test method can obtain the circumferential strain and axial strain in internal grain. The research results can lay a foundation for the further application of fiber bragg grating sensor in the measurement of solid motor grain structure, and can provide a reference for the development and application of solid motor monitoring and detection technology.