The invention discloses an involute internally meshed gear pump with two sides of a crescent plate having dynamic lubricating effect. The gear pump comprises a pump body, a transmission shaft, an outer gear, an inner gear, the crescent plate and an end cover, wherein the inner gear is arranged on the transmission shaft. By offsetting the inner side profile center of the crescent plate to an oil suction side relative to the center of a driving gear and offsetting the outer side profile center of the crescent plate to an oil pressing side relative to the center of a driven gear, a convergent oil wedge structure, which has a maximum gap value at the oil suction side and has a minimum gas value at the oil pressing side, is formed at the inner and outer sides of the crescent plate; the dynamic lubricating effects of the inner and outer sides of the crescent plate can be sufficiently exerted by virtue of the convergent oil wedge, so that the lubricating performance of the internally meshed gear pump is improved and the volume efficiency is increased.