Purpose. Development of an approximate analytical method for calculating strength reduction of different rocks under thermal cycling effects, taking into account the intensity of convective heat transfer. Methodology. To solve the problem, an analytical approach based on the thermoelasticity theory was used within the frame work of the Griffiths model of fragile fracture. Findings. It is demonstrated, that cooling of the previously heated rock formation stipulates for intensifies of the rock decom position process, due to developing fractures zone and decreasing rock strength. Methods for calculating were developed and effect of the intensity of convective heat transfer on crack opening processes in the rock was studied. The results of calculation of destruc tion time lag for various rocks are presented. It is shown that the efficiency of thermal cyclic decomposition depends on the type of rock. Originality. A new approximate analytical approach to the investigation of the development of initiated cracks in mining rocks under thermal cyclic load and cooling applied to the surface is proposed. An analytical expression has been obtained for the rela tionship between the parameters of the fracture process and the parameters of the cooling process. Theoretical substantiation of the use of variable thermal effects on the rock to improve the efficiency of rock destruction during drilling has been carried out. Practical value. The outcomes of the study can be used to estimate of the parameters of the heat exchange processes to provide effective rock disintegration during drilling. The studies carried out confirmed the possibility of control of the temperature mode on the working face and thermal softening of the rock by changing the flow rate of the drilling fluid.