A low-cost and high efficient tunable terahertz (THz) bandpass filter on aluminum slab with a center slit flanked by symmetrically distributed parallel grooves on both sides was experimentally analyzed by the terahertz time domain spectroscopy (THz-TDS).Experimental results show that a high centre transmittance (>95%) can be obtained at 0.33 THz because of the enhanced transmission effect induced by symmetrically coupled spoof surface plasmon polaritons (SSPPs).And the transmitted THz wave radiated from the slit aperture has a small divergence angle (approximately 5°).Moreover, the transmission peak splits into two peaks: the low-frequency peak shows redshift and the high-frequency peak shows blueshift when the incident tilting angle increases, and the transmission peak blue shifts when the incident pitching angle increases.