The family Agonidae comprises small to medium-sized fishes armored with bony plates, dwelling in the demersal waters of mid to high latitudes globally. To date, 24 genera and 54 species have been documented worldwide, with 4 genera and 5 species identified in China. During the examination of specimens in the collection of the Shanghai Ocean University, two specimens of Percis japonica (Pallas, 1769) were discovered, one of which, collected from the northern Yellow Sea in 1965, represents a new species record for China (Fig. 1). This study conducted detailed morphometric analyses on the specimen and compared it with another specimen from the Bering Sea stored in the same collection (Table 1). The main morphological characteristics are:mouth terminal, with the snout lacking prominent barbels; dorsum highly elevated at nape, dorsal fins rays V﹣VI, 6﹣8, anal fins rays 7﹣9, few middorsal plates, complete absence of midventral plates; body presents a light brown hue, flanks marked by several dark transverse bands. Additionally, a key to the 4 genera and 6 species of the family Agonidae recorded in Chinese waters is provided herein. This study lists the main identification characteristics of P. japonica. and underscores the latent value of museum specimens in the detection of newly discovered species.