Abstract: KFTA solar simulator is an off-axis collimation solar simulator attached to KFTA thermal vacuum environmental simulation facility, with an off-axis angle of 25? and an irradiation area of 600 mm in diameter. The incidence of light is in the horizontal direction. In the development of KFTA solar simulator, the technology of horizontal ignition of the xenon lamp is selected, which means a certain degree of technical difficulty and risk. This paper presents the design and calculation of KFTA solar simulator, including project design, system design, key technologies, system test. Successful construction of KFTA solar simulator paves a way for developing a large solar simulator.