With the wide application of radar seeker on missile, the anti-jamming capability of the seeker is a key technology. The radar frequency synthesizer is the core part of radar system. The quality of local oscillator signal generated by radar frequency synthesizer shows a critical impact on the radar system’s ability of confrontation and anti-confrontation. Therefore, it proposes higher requests on the parameters of the local oscillator signal including wideband hopping, phase noise, clutter suppression, flatness and so on. Based on Direct Digital Synthesizer(DDS) technology and Advanced Design System (ADS) simulation technology, broadband impedance matching is performed. The effective signal crosstalk isolation technology is adopted to improve the indexes of X-band local oscillator signal of the radar frequency synthesizer. Through experimental testing, the local oscillator signal can achieve fast frequency hopping, and the frequency hopping bandwidth reaches 500 MHz, which improves the anti-interference capability of the radar; the phase noise is better than -98 dBc/Hz@1 kHz, which effectively improves the receiving sensitivity of the radar seeker.