The experimental results on steady-state and transient photoconductivity of amorphous (As₄S₃Se₃)_1-xSn_x (x = 0÷0.1) thin films are investigated. Arsenic selenide glasses are well known as high photosensitive materials with a wide range of application in optoelectronics and information storage systems. Besides, that it was found that the impurities influence the electrical, photoelectrical and optical characteristics of the amorphous material, due to the changes in the density of localized states. Introduction of the elements of IV group of periodic table in selenide and sulphide glasses, such as Sn, conduct to the appearance of tetrahedral structural units in the base glass, which change the coordination number and other parameters. These particularities lead to the non-monotonic dependence of mechanical, electrical, optical and photoelectrical properties with increasing of the concentration of four coordinated atoms. It was shown, that the spectral distribution of the stationary photoconductivity for studied glass system depends on the composition and polarity on the illuminated electrode. The dependence of the stationary photocurrent I_ph on the light intensity F for the exponential distribution of the localized states is described by a power function I_ph ~ F^α, were the parameter 0.5 ≤ α ≤ 1.0. The transient photocurrent behavior in investigated amorphous materials is controlled by carrier localization and delocalization processes. The kinetics of photocurrent produced by uniform continuous bulk photogeneration of non-equilibrium carriers reveal anomalous behavior, passing through the maximum before the stationary state is reached. The relaxation curves are described by the parameters of the localized state energy distribution, and are analyzed in the framework of multiple trapping models for amorphous materials.