Insufficient insolation condition is one of the urgent problems to be solved in north China because of its cold climate and smaller solar elevation angle. To improve this situation, we are working on a theoretical model for optical facilities based on the principles of rays refraction, which can concentrate solar energy from larger scope to smaller scope, then insolation standard can be improved in the specific region. A theoretical model on the structures and working principles of the insolation lens is explained in detail, its validity is proved by optical simulation, and trajectory of rotating Insolation Lens is analyzed at length. This theoretical model could improve the insolation conditions of the existing residential buildings and reduce the land use in the urban construction processes.