Our work develops a novel pathway for controllable and tunable spintronics and optoelectronics devices. The biaxial strain and doping functions on electronic structure, magnetic and optical properties were explored with the method of density functional theory (DFT). Results show that the Cr-doped antimonene is a narrow indirect band-gap semiconductor (0.44 eV), and the valence band maximum (VBM) changes from K to Gamma point due to spin-orbit coupling (SOC) interaction. Hence, there exists a remarkable spin splitting near E-F caused by the coexistence of strong p-d hybridization and SOC effect. The total net magnetic moment is 3.00 mu(B) in Cr-doped antimonene system, while the coupling interaction between them is anti-ferromagnetism (AFM) order, which facilitates its use in AFM-based spintronic devices. For the case of coexistence of strain and Cr dopant, the Cr-doped system transforms from magnetic semiconductor to magnetic half-metal material under the biaxial tensile strain of 6%. Most interestingly, the band gap closing can be achieved when biaxial strains range from -4% to -6%, so these systems present metal characteristics. Comparing with the unstrained doping system, the local magnetic moments increase to 4.49 and 5.00 mu(B) at biaxial tensile strains of 6% and 8%, respectively. More importantly, we found that the absorption efficiency of visible light can be increased by Cr incorporation as well as biaxial compression strain applied to the Cr-doped antimonene system.