An inverted 3-FOV(field of view) Schmidt telescope based on 3-facet mirror was developed, and its key technical problems were studied. Based on the geometric symmetry of regular triangular pyramid, the relationship between the visual axis angle of 3 FOVs and the angle of facet mirror was derived, and a 3-facet mirror was designed to realize the multi-field observation function. The influence of the gravity deformation of primary mirror of inverted Schmidt telescope on the image quality was analyzed by finite element method. The influence of the key parameters of testing optical path on the processing error of Schmidt corrector was expounded. The stray light of optical system was studied by Monte Carlo method. Finally,the whole optical system was tested experimentally, and a 3-facet mirror was actually developed. Results show that the included angle between the mirrors is 133.08°, which can observe 3 FOVs perpendicular to each other at the same time. The test result of the telescope optical system is PV=0.614 λ, RMS=0.105 λ (λ=632.8 nm). The system can be used to measure the earth attitude in space, which expands the application of Schmidt telescope.