In this paper, we report a simple and green strategy for the synthesis of hydroxyapatite (HAP) nanostructures with various morphologies (including nanoparticles, microtubes, nanorods and nanorod-assembled flower-like hierarchical structures) using adenosine 5′-monophosphate sodium salt (AMP) as an organic phosphorus source by solvothermal treatment in different solvents. The effects of the solvents and the reaction time on the morphology of the product as well as the formation mechanism of HAP nanostructures are investigated. In this strategy, the AMP biomolecules act as an organic phosphorus source for the formation of HAP nanostructures, and the solvents have effects on the morphology of the product. This strategy is environmentally friendly and surfactant-free. The as-prepared products are characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TG).