Boron nitride (BN) nanoparticles with high surface area were prepared by temperature-programmed nitridation and temperature-programmed reduction methods. The catalytic activity of the Ru-Ba/BN ammonia synthesis catalyst was studied. Characterizations by X-ray diffraction, N(2) adsorption-desorption, scanning electron microscopy, and Fourier transform infrared spectroscopy were performed to study the crystalline structure, pore structure, and surface properties of the BN material. The characterization results showed that using the above two methods can prepare hexagonal boron nitride with higher surface area, being 103 and 138 m(2)/g, respectively. The outlet ammonia concentration reached 7.3% under the conditions of 475 degrees C, 10 MPa, and 10 000 h(-1) for the Ru-Ba/BN catalyst, and the activity was stable after thermal treatment at 550 degrees C for 30 h.