A new species, Alexeterbeijingensis Sheng, sp. nov., and two new records for China, A.angularis (Uchida, 1952) and A.shakojiensis Uchida, 1930, collected in Mentougou, Beijing, belonging to the tribe Mesoleiini of the subfamily Ctenopelmatinae (Hymenoptera, Ichneumonidae), are reported. A key to the six species of Alexeter known from China is given.