Spatial (three-dimensional - 3D) computer model of the T-x-y diagram of the Ag - Cu - Ni system, which is promising for the development of environmentally friendly solders, is presented. The model is constructed on the basis of published data on the binary systems forming this ternary system, the concentration projection of the liquidus surfaces, and four isothermal sections. It is shown that the phase diagram (PD) consists of 14 surfaces and 9 phase regions. The adequacy of the model is confirmed by comparing the isothermal sections and the liquidus projection.