Regular black phosphorus (BP) sheets possess strongly anisotropic properties due to the unique puckered atomistic configuration, making such BP mechanically very weak in the armchair direction. The present work aims to address this issue by proposing an angle-ply double-layer black phosphorus (DLBP) structure in which two individual atomic layers with different orientation angles are stacked up. The molecular dynamics simulations based on Stillinger-Weber potential show that the in-plane mechanical properties of such a DLBP structure, e.g., Young's modulus and tensile strength are significantly influenced by the stacking angle of each layer. The property anisotropy of DLBP decreases as the stacking angle difference δ between two layers increases and becomes isotropic when δ = 90°. This work also shed insight into mechanisms of angle-ply layers underlying the mechanical behaviors of DLBP at the nanoscale, suggesting that the anisotropic material properties can be effectively controlled and tuned through the appropriately selected stacking angles.