Abstract: The separation and determination of a rice paddy herbicide 2-(2-naphthalenyloxy)-N-phenyl propanamide (napropanilide) has been studied by gas chromatography, using Φ6×1.5×1500 glass column packed with 5% OV-7/Chromosorb W-AW DMCS, size(0.387～0.321 mm) and di (2 ethylhexyl) phthalate as internal standard with correction factor f_W.A=0.978±0.005. It is simple, fast and accurate method for determination of naproanilide. The repeated analysis of a same sample gave the method standard deviation is less 0.90 and a coefficient of variation less 1.18%. The recovery of the method was 99.38%～101.8%.