Abstract: The No.1 cave and other four caves of Longyou Grottoes have been used for tourism and research over sixteen years. Within these years, plentiful and substantial socioeconomic performance and academic achievement have been obtained. But, these caves have been damaged to some extent by action of natural powers. Pillars, walls and roofs of the grotto have been cracked, because argillaceous sandstone forming the caves are prone to weathering and flowing deformation, and destruction by reasons of alternation of wetting and drying and temperature fluctuation. Roofs, pillars and walls of the caves were failed in the mode of punching shear, shearing and bending under action of weight because of insufficient strength, and external force in the process of exploitation aggravated the destruction. Layout of reinforcement should adopt integrated design and be carried into execution step by step for these failure modes. Pillars and walls should be reinforced firstly, and then roof of caves. Pillars and walls should be reinforced by pillars mostly and the roofs should be reinforced by beams. Both reinforcement instruments should be connected and form an artistic reinforcement system.