Chromium and vanadium influence to different modification pyrrhotite structures was researched by X-ray method. Solid solutions Fe0,94.x(Cr,V)xS and Fe0,0875-x(Cr,V)xS were obtained to be crystallized as PoP in the range of x up to 0.04. Unit cell parameters of Pom, Poll and the solid solutions Poll with chromium and vanadium were defined. Obtained data are useful for explanation of pyrrhotite forming mechanism and for the development of influence methods to sulfide phase structure.