The strong magnetic phase size and its magnetic properties in FeCrCoVTiW permanent alloy were measured by Mssbauer spectrum and transmission electron microscope. The compositions of the two phases in the alloy were analyzed. The components of the 1 phase is 78Fe5Cr17Co, the components of the 2 phase is 13Fe80Cr7Co. According to the single magnetic domain theory, the computed value of coercive force of the alloy is approximately consistent with the experimental value, and the high coercive force value is resulted from the magnetic moment turn in the single magnetic domain of the alloy.