Abstract: Compared with thin-screen FSS, thick-screen FSS presents high Q-value characteristics and can get the same effect with less matching media; Meanwhile, thick-screen FSS has advantages in application since it is made of metal plate by means of mechanical processing which can get precise processing sizes. In this paper a thick-screen FSS structure with circular holes was designed and simulated by means of FDTD. The influence of the structure parameters, such as unit cycle, unit size and screen thickness, on its transmission characteristics was studied and the results are as follow: On one hand, with the increase of the cycle and screen thickness, bandwidth reduces and center frequency point decreases; On the other hand, with the increase of unit size, the bandwidth increases and the center frequency point decreases. Furthermore, based on the design results, thick-screen FSS samples were prepared by means of mechanical processing and were tested in microwave anechoic chamber. The results were compared with the simulated data which verified the rationality and accuracy of the design and simulation. This offers references for the further research and practical application of thick-screen FSS.