For requirements of a high-resolution radar system for wider bandwidths, higher linearity and longer time delays in the echo simulation, a compact Microwave Fiber Delay Line (MFDL) was designed for measurement and calibration of X-band radars. The performance requirements of a radar echo simulator for the distance delay unit was analyzed. The key component, a directly-modulated Distribution Feedback( DFB) laser, was developed according to the system specifications to implement the linear electro-optic conversion of broadband radar signals. Then, a compact reflective delay line structure was designed and realized based on a fiber mirror. Finally, a vector network analyzer was utilized to measure and analyze the microwave transmission properties of the MFDL. Experimental results indicate that the -3dB analog modulation bandwidth of the DFB laser is up to 21 GHz. The MFDL based on the DFB laser provides the time delays by 40 μs, 80 μs, 120 μs for different targets on typical X-band radar test application, in which the in-band amplitude flatness and phase nonlinearity are less than ±0.5 dB and 10°, respectively, and the system dynamic range is larger than 60 dB. The designed MFDL meets the requirement of radar echo in simulation and calibration for additional amplitude errors and phase errors.