The paper proposes a computer-aided way for culture heritage protection and restoration, which is based on virtual navigation and image processing technologies. It first creates the database for the digital information of the cave construction and the mural and also provides some operations, such as insert, query etc., for the database management. In a virtual environment of the cave, users can navigate, mark the disease area, inquire for information about the mural, monitor and analyze the environment data, and also do virtual mural restoration and simulate the mural evolution without damaging the heritage itself. The article introduces the following technologies: virtual construction of the cave, knowledge expression of Mural, interactive disease marking, object extracting, color restoration with mural knowledge, color harmonization for simulating the mural evolution, and also the functions, modules, workflow of our system.