Abstract: Although bulk SnP₃ has been fabricated by experiments in the 1970’s, its electronic and optical properties within several layers have not been reported. Here, based on first-principles calculations, we have predicted two-dimensional SnP₃ layers as new semiconducting materials that possess indirect band gaps of 0.71 eV (monolayer) and 1.03 eV (bilayer), which are different from the metallic character of bulk structure. Remarkably, 2D SnP₃ possesses high hole mobility of 9.171×10⁴ cm²?V^-1?s^-1 and high light absorption (∽10⁶ cm^-1) in the whole visible spectrum, which predicts 2D SnP₃ layers as prospective candidates for nanoelectronics and photovoltaics. Interestingly, we found that 2D SnP₃ bilayer shows similar electronic and optical characters of silicon.