An ideal scaffold should have good biocompatibility and osteogenic differentiation properties and provide interconnected porous networks for cell penetration and nutrient and waste transportation. To improve the biological activity of hydrogels, with nano-β-tricalcium phosphate (TCP) as a model, we successfully designed β-TCP nanoparticle/hydrogel encapsulated scaffolds, which improved the osteogenic differentiation ability of bone marrow mesenchymal stem cells (BMSCs) and focused on the osteogenic differentiation mechanism of the β-TCP nanoparticle-mediated microenvironment and phosphorus. Results showed that β-TCP nanoparticles affected phosphorylated ERK1/2 and BMP-2 signalling molecules in BMSCs through ATP metabolism. Addition of an ATP inhibitor (NEM) and SLC20a1 inhibitor (Foscarnet), significantly inhibited expression of phosphorylated ERK1/2 and BMP-2. This study also provides an understanding of the positive role of β-TCP nanoparticles and β-TCP nanoparticle/hydrogel-encapsulated scaffolds in the bone repair field.