The applications of terahertz Frequency Selective Surface(FSS) in radioastronomy, satellite remote sensing, and air borne radiometers have been reviewed, with the focus placed on the design, fabrication and testing of terahertz FSS. Numerical methods and commercial electromagnetic software are discussed for FSS design and analysis. Due to the physical dimension of terahertz FSS, the performance is subjected to the fabrication precision compared to their counterparts in lower frequency range. In consequence, micro/nano-fabrication techniques are preferred in the fabrication. Fabrication precision should be included in the design phase. Multi-echo waves should be avoided in the testing.