A kind of strain measurement system of electromagnetic railguns based on Bragg Grating technology was introduced in this paper. The Bragg grating strain measurement system of electromagnetic railguns was designed. The data processing and the calibration of the measurement system were discussed. The experiments of strain measurement in electromagnetic launch were accomplished. The results show that the Bragg grating strain measurement system can work reliably in strong electromagnetic interference, which satisfied the special demand of anti- electromagnetic interference for the strain measurement system.