Using the method of physico–chemical analysis there have been examined the nature of chemical interaction in the triple system of Tm –Bi–Te on polythermal sections Bi2Te3–Tm3Te4 , Bi2Te3–Tm, TmTe–Bi, TmTe –TmBi, TmBi4Te7(S1) –Bi, TmBi4Te7 – Tm3Te4 .There have been constructed diagrams of sections state and the deviced liquidus surface of the triple system. The fields of primary crystallization of phases, the triple compounds TmBi4Te7 , TmBi2Te4 and TmBiTe3 have been established. The first of them is melted congruently to take part in the triangulation of the triple system. There also have been defined the types and coordinates of non-and monovariant equilibriums on phase diagram.