Abstract: This paper discusses the technical specifications of typical large solar simulators abroad, and the key technologies of their development. The key technologies include the choosing of light source, the way of ignition, the optical system design and alignment, the performance measurement and cooling of the solar simulator, all of which have an important bearing for developing the KM6 solar simulator in China. The general design scheme of the KM6 solar simulator is discussed. In this scheme, the moderate power xenon lamp is proposed as the light source, and the horizontal operation of the lamp instead of the vertical operation is considered, to avoid 15% energy loss due to the existence of the reflective mirror.