A new type of terahertz photonic crystal filter is presented, which includes the waveguide parts realized by line defects, and the frequency selection parts realized by micro cavities. The band gap property was investigated by using plane wave method (PWM), and then the transmission characteristic of terahertz in this kind of filter was studied by means of the finite difference time domain method (FDTD) simulation. The results show that, the filter can achieve high coupling efficiency filtering of single-channel and single-frequency, by changing the point defects structure and increasing the radius of certain dielectric cylinder. High efficiency THz-band photonic crystal filter was designed in this thesis.