Abstract:〗A new selenoid (lunar geoid) is derived using the lunar gravity model CEGM02 and topography model LRO_LTM02, which approximates the physical surface as closely as possible. The estimated gravity potential value of this selenoid is 2 822 327.8±16.2 m2/s2, denoted as W0 in usual. A triaxial level ellipsoid whose surface gravity potential equals W0 above is calculated and used as a reference ellipsoid, and its semimajor axis, polar flattening, equator flattening and longitude of semimajor axis are 1 737 462 m, 1/2 579, 1/6 863 and -76.8 ″, respectively. Based on this reference ellipsoid, the gravity decreases about 60×10-5ms-2 from the equator to the poles, while the variation along the equator is about 25×10-5ms-2. The selenoid undulations are in the range of -325.9 m to 389.1 m.