The Chi blocks (Chi block 1, 2, and 3) are new armor units developed by KIOST to reduce the intensity of wave energy. In this study, uniform placement in single layer is proposed for Chi blocks and the corresponding stability coefficients are determined. 3-point separation technique is used to separate incident significant wave height and reflected significant wave height. Hudson formula is used to calculate the stability coefficient with the incident signnificant wave height. In order to determine the most economical block between Chi blocks, the void ratio is calculated. Chi block 2 is the most stable block because its stability coefficient is the highest value and Chi block 1 is the most economical block because its void raio is the highest void ratiovalue. The stability coefficient of Chi block for uniformly x-shape placement method is compared with Because the stability coefficients of all Chi blocks are bigger than stability coefficient of Tetrapod, which is used frequently in Korea, Chi blocks are suitable blocks to withstand the abnormally high waves in Korea.that of Chi block for other placement method. In addition, the stability coefficient of Chi block is compared with those of other armor units such as Accropode, Core-loc, and X-bloc (single-layer), and Tetrapod and Dolos (two-layer).re determined. 3-point separation technique is used to separate incident significant wave height and reflected significant wave height. Hudson formula is used to calculate the stability coefficient with the incident signnificant wave height. In order to determine the most economical block between Chi blocks, the void ratio is calculated. Chi block 2 is the most stable block because its stability coefficient is the highest value and Chi block 1 is the most economical block because its void raio is the highest void ratiovalue. The stability coefficient of Chi block for uniformly x-shape placement method is compared with Because the stability coefficients of all Chi blocks are bigger than stability coefficient of Tetrapod, which is used frequently in Korea, Chi blocks are suitable blocks to withstand the abnormally high waves in Korea.that of Chi block for other placement method. In addition, the stability coefficient of Chi block is compared with those of other armor units such as Accropode, Core-loc, and X-bloc (single-layer), and Tetrapod and Dolos (two-layer).