The invention relates to an effect-losing damage simulation system for a composite seepage-proofing liner. The system belongs to the technical field of environmental geotechnics. The simulation system is composed of a control platform, an observation device and a simulation device. Hydraulic telescopic rods evenly arranged in a simulation container of the simulation device in a matrix mode are respectively controlled by a hydraulic control valve to change in different heights, and the deforming situations under the working conditions of differential settlement deformation for the composite seepage-proofing liner can be effectively simulated, temperature and pressure of test solution affected on the composite seepage-proofing liner can be controlled and adjusted according to test working conditions, a three-dimensional camera device monitors differential settlement of the composite seepage-proofing liner in real time through a marking ball of the simulation device, test parameters is set on a control platform which acquires and processes test data, and test efficiency is greatly improved. The simulation system can effectively simulate effect-losing damage of the composite seepage-proofing liner under mode effects of different solution density, temperature, pressure and differential settlement.