Two-dimensional (2D) ferromagnetic (FM) materials have great potential for applications in next-generation spin-tronic devices. Since most 2D FM materials come from van der Waals crystals, stabilizing them on a certain substrate without killing the ferromagnetism is still a challenge. Through systematic first-principles calculations, we proposed a new family of 2D FM materials which combines TaX (X=S, Se or Te) monolayer and Al2O3(0001) substrate. The TaX monolayers provide magnetic states and the Al2O3(0001) substrate stabilizes the former. Interestingly, the Al2O3(0001) substrate leads to a metal-to-insulator transition in the TaX monolayers and induces a band gap up to 303 meV. Our study paves the way to explore promising 2D FM materials for practical applications in spintronics devices.