Noncombustible Mg-8Al-2Ca rods were processed by RD-ECAP. The magnesium alloy rod had Mg matrix and Al2Ca second phase. Grains with about 20 μm in diameter were observed in the matrix of the raw materials. The grains in matrix had no anisotropy. On the other hand, positions of second phase particles had anisotropy and the second phase particles formed lines. The samples processed by RD-ECAP had no crack and the samples had 20mm diameter. Grains in matrix of the 4 pass RD-ECAP sample had no anisotropy and the grains had under about 5 μm in diameter. The second phase particles had round shapes and were uniformly distributed as compared with the raw material rod. Therefore, the RD-ECAP is useful for forming noncombustible Mg-8Al-2Ca alloy with fine-grains.