•Ordered mesoporous B-doped alumina with large pore size was obtained by using urea.•Ordered mesoporous boron-doped alumina has high surface area and tunable pore size.•Ordered mesoporous boron-doped γ-alumina can resist high temperature up to 1000 °C.Ordered mesoporous γ-alumina with high surface area and large pore volume has been successfully synthesized via a simple sol-gel method using urea as pore-enlarging agent and acetic acid as interfacial protector. The boron dopant stabilizes the mesostructure and the introduction of urea enlarges the pore volume, which effectively improves the surface area and thermal stability of the as-synthesized ordered mesoporous alumina. The obtained boron-doped γ-alumina prepared with urea maintains ordered hexagonal mesostructure with a large pore size (11.8 nm) and large pore volume (0.88 cm3 g−1) after calcined at 1000 °C, indicating its excellent performance of resistance to sintering under high temperature.