The invention relates to technical physics and can be used in the production of light-absorbing and light-emitting semiconductor devices, such as solar cells, photodiodes, light-emitting diodes, etc. The aim of the invention is to develop a technique, to initiate phase transition from SnS2 to SnS and from SnS to the metallic phase of tin by the use of Nd:YAG, Nd:YLF, Yb:KYW or Nd:YAP pulse laser irradiation of crystalline SnS2 sample surface. The offered initiation method of phase transition in tin sulphide, which includes initiation of the phase transition at the surface of SnS2 by laser irradiation, with absorption coefficient of SnS2 not less than 104 cm-1 and not more than 105 cm-1, with laser intensity from 7 to 12 MW/cm2 and with pulse duration from 1 to 10 ns, results in formation of SnS layer with thickness equal to or less than 5 µm. Laser irradiation of SnS, with absorption coefficient in SnS not less than 104 cm-1 and not more than 105 cm-1, laser intensity within range from 12 to 15 MW/cm2 and pulse duration from 1 to 10 ns, results in formation of the metallic phase of tin on the top layer of SnS surface with thickness equal to or less than 5 µm.