Abstract: The pendulum-type wave is a special rock mass dynamic phenomenon in deep rock mass engineering. It is the propagation with low frequency and low speed in rock mass, which carries the obvious energy propagation. According to the energy transfer rules in the propagation process of pendulum-type waves in block-rock mass, the laws of the energy transformation between rock block and nearby weak medium is studied based on the block-hierarchical theory of deep rock mass which is composed of discontinuous and self-balance stress block-rock. The laws of energy transfer in block-rock mass with self-balance stress are investigated through analysis. The energy conversion in the block-rock mass is the mutual transformation between the kinetic energy of the rock block and the elastic potential energy of the nearby weak medium during propagation of pendulum-type waves. The kinetic energy and elastic potential energy transfer forward on during mutual transformation of energy. The expression for energy transfer and transformation in block-rock mass is given. Through calculation and analysis, the laws of energy variation in local area exhibits cyclic attenuation, and the variation and dissipation of kinetic energy and elastic potential energy have exponential relationship in the whole block-rock mass.