The electromagnetic wave (EMW) shielding effectiveness characteristics of the structure which carbon fiber arranged like grid in the frequency of 0.5 ~ 2.0 GHz were studied in this paper. The results showed that the EMW shielding effectiveness of this structure are affected greatly by the space between carbon filaments. In addition, the results also showed that the mechanism of EMW attenuation of grid arrangement is similar as grid shape fabric and complementary to parallel arrangement in the measured frequency.