Indium selenide (InSe) is a promising two-dimensional photodetector material. However, the photogenerated electron-hole pairs are easy to recombine in simplex InSe semiconductor. Here, we design InSe-based van der Waals heterostructure, InSe/antimonene (beta-Sb), based on first-principles. InSe/beta-Sb heterostructure possesses intrinsic type-II electronic structure. Simultaneously, the work function of InSe (beta-Sb) layer is -5.7 eV (-4.5 eV) which also promotes electrons transfer. In addition, the good optical absorption performance of InSe and beta-Sb sublayer is preserved in the heterostructure. Moreover, different stacking mode between InSe/beta-Sb does not affect the efficient carrier separation which is convenient to the application of optoelectronics.