Abstract: The foundation of the computer simulation for the phase analysis of alloys vising phase e-quilibrium calculation has been expounded. The phases presented in the microstructure of W6Mo5Cr4V2, W10Mo4Cr4V3Al and Mo5Cr4V high speed steels at the quench-heated state and the anneal-heated state have been analyaed differently, and the necessary information concerning the phase constituents in the steels at the states mention above and their variation has been obtained.