According to the technical requirements of rocket sled track parallelism measurement, a design scheme of portable and high-precision track parallelism measurement instrument is proposed. Carbon fiber is used as the main material, and the technologies of grating displacement sensing, precision tilt angle measurement and temperature correction are used, and the errors are analyzed comprehensively. The results show that the high-precision measurement results can be obtained in the outfield environment, and the relevant performance indicators meet the technical requirements of rocket sled track detection.