Filter order is the core parameter affecting the time-domain adaptive anti-jamming performance and the computational complexity of satellite navigation receivers. In order to solve the problem that the current order selection is heavily dependent on engineering experience and the impact of the analysis is insufficient, the impact of the filter order on the time-domain adaptive anti-jamming performance of navigation receivers was analyzed, providing theoretical research for low-complexity time-domain anti-jamming. The analysis was oriented to different interference environments. The filter amplitude-frequency response and the signal carrier-to-noise ratio were used as evaluation indicators. The simulation experiments and practical tests verified the traditional LMS(least mean square) algorithm and the improved LMS algorithm. Finally, an adaptive design method for optimal filter order based on digital filter was proposed. Experimental data analysis shows that the anti-interference performance of the time-domain adaptive filter can be effectively improved by appropriately increasing the filter length. In practical applications, the filter order can be optimized by constraining the carrier-to-noise ratio loss.