Detachment is one of the most serious deteriorations in murals. It is an urgent issue to address as it is significant to the conservation of our precious culture objects. Based on the basis of simulated laboratory experiments and in-situ tests in the case of conserving detached murals in Tibet, this paper systematically summarizes the principles, materials and techniques for conservation through grouting. The criteria for choosing the position where grouting and anchoring holes should be set, the setting of pipes, the control of water-ash ratio and grouting amount, the function of physical support for the mural when grouting, the technical requirements for consolidation by grouting and accessorial anchoring, the standard and principle for painting restoration, the assessment of the grouting effect, the development of grouting equipment and other crucial technical issues are discussed emphatically. It concludes that grouting with accessorial anchoring is one of the main treatment for detached murals.