B0.54C0.28N0.18 precursor powder with turbostratic structure was prepared by using melamine and boric acid. The precursor was transformed into orthorhombic B2CN under definite high pressure and temperature conditions. The composition of the orthorhombic B2CN powder is B0.47C0.23N0.30. Its lattice parameters are a = 0.4776 nm, b = 0.4585 nm and c = 0.3629 nm. A strong absorption band from 1088 to 1385 cm(-1) of orthorhombic B2CN was observed by infrared measurement. In the photoluminescence (PL) spectrum of orthorhombic B2CN powder measured at room temperature, a broad peak corresponding to its band-edge emission centers at 374 nm.