A smoke detecting enclosure which is impervious to interference from outside light sources includes a smoke detecting housing and an upper cover. The smoke detecting housing has an receiving space with openings on one side, an opposite side defines two opposite installation parts carrying a light emitter and a light receiver. A peripheral surface of the smoke detecting housing is a first terraced wall and the upper cover when coupled with the opening comprises an open-ended cavity and a light barrier. The light barrier is opposite to the opening and is on an open path to the opening. A smoke detector is further disclosed.