Abstract: In order to liberate coal under reservoir dam and to improve the mining rate of the coal resources, with the theoretical analysis, simulated calculation, sit e observation and other method, a top coal caving coordinated mining technology of the thick seam under the reservoir dam was provided.Five factors of the coal minin g face forward direction, mining size, location, mining sequence and pushing forward speed were firstly considered and a model of the top coal coordinated mining with the five factors in the thick seam under the reservoir dam was provided. Based on the circumstances, the paper analyzed and calculated the two zone heights of the top coal mining in the thick seam and the displacement and deformation value of the reservoir dam after the top coal coordinated mining conducted.The paper studied the s afety of the top coal mining under reservoir dam and the mining influence degree to the dam.A surface ground displacement observation station was established on the reservoir dam to have a dynamic monitoring and measuring of the reservoir dam.The study results showed that the coordinated mining model with the five factors applie d to the coal mining under reservoir dam was feasible.The top coal safety mining in the thick seam under reservoir dam was realized and no tensile deformation crack 0 ccurred in the reservoir dam.