A new species of free-living marine nematodes that belongs to the family Richtersiidae Kreis, 1929 was found in the Yellow Sea and is described herein as Richtersia sinica sp. nov. The new species is characterized by a body length of 402–430 μm; a multispiral amphidial fovea with 4–4.5 turns in males and 1 turn in females; longitudinal rows of spines beginning at the mid-pharyngeal level in both sexes; paired spicules that differ in both shape and length; the right spicule being slender and elongated, 3.9–4.9 times cloacal body diameter in length, with a bifid proximal end; the left spicule being thick and short, 1.7–2.3 times cloacal body diameter with an enlarged cephalate proximal end; the gubernaculum being plate-shaped, gradually narrowed at both ends, lacking apophyses; and the tail short and conical. An updated key for the identification of valid species of Richtersia is provided.