In this paper, a terahertz low-loss transmission line based on spoof surface plasmon polaritons (SSPPs) is proposed, and a terahertz rejection filter with high isolation is demonstrated by loading split-ring resonators (SRRs). The SSPPs-based transmission line is optimized by an irregular gradient transition structure, and thus its transmission loss and unevenness in the terahertz frequency band are reduced. Then, the frequency band suppression mechanisms of the SSPPs-based transmission line loaded with SRRs and without SSRs are revealed through the dispersion analysis. When the SSPPs-based transmission line loaded with SRRs operates under the fundamental mode and the first-order high mode separately, its fundamental mode is characterized by low pass while its first-order high mode features bandpass, and thus the terahertz filtering characteristic of pass-stop-pass-stop is achieved. In addition, by adjusting the geometric parameters of SRRs, we can control the stop-band frequency of the SSPPs-based filter and improve the suppression depth of the SSPPs filter by increasing the number of loaded SRRs. To demonstrate the feasibility of the design, this study conducts terahertz on-wafer tests for the proposed SSPPs-based transmission line and filter prepared by micro-nano fabrication. The results reveal that in the frequency band of 0.11-0.17 THz, the insertion loss of the SSPPs-based transmission line is less than 0.5 dB/mm, and the return loss is better than 10 dB; in the frequency band of 0.142-0.156 THz, the suppression depth of the SSPPs-based filter is greater than 10 dB, and the maximum suppression depth is up to 45 dB at 0.148 THz. The experimental results are in good agreement with the simulated ones. The research is of great significance to the integrated system of terahertz plasmons.