The invention discloses an environment-friendly and energy-saving fabricated building, and particularly relates to the field of environment-friendly and energy-saving buildings. The environment-friendly and energy-saving fabricated building comprises a fixed base, multiple wallboards are arranged at the top of the fixed base, a supporting column is arranged between every two adjacent wallboards, an adjustable roof is arranged at the top ends of the supporting columns, and the adjustable roof is fixedly connected with the wallboards. According to the environment-friendly and energy-saving fabricated building, through cooperative use of the adjustable roof and a transmission mechanism, an adjusting disc body is rotated anticlockwise, through transmission of a transmission chain, a transmission gear and a linkage rod, multiple shading plates synchronously rotate along a steering shaft, sunlight can irradiate into a room through gaps between the adjacent shading plates for light supplement, during the period, a reflector can refract and irradiate the light with the inclination angle into a room, light supplement is conducted on the shadow formed when sunlight irradiates the positions of the shading plates, so that the indoor light is sufficient and uniform, the sufficient illumination intensity is guaranteed, on one hand, the electric power illumination duration can be shortened, on the other hand, indoor moisture exhaust can be accelerated, and the service life of the building is prolonged.