“Black silicon” can be formed by different methods, such as chemical, electrochemical etching and laser assisted chemical etching. Si structures produced by these methods can be used for solar cells, sensors, medical application and etc. In this work we present investigation of optical properties of “black silicon” formed by laser radiation, depending on formation circumstances. The formation of structures by laser radiation is clean and ecological method. The shape and height of micro-cone structures strongly depend on Nd:YAG laser intensity and number of laser pulses. SEM-EDX and photoluminescence methods were used to investigate the “black silicon” structures. The investigation of UV-VIS radiation spectra of Si micro-cone structure shows that they are similar to “black body”, which makes these structures useful for solar cells application.