Thermal stress deformation is a disadvantage of the rotary air preheater, which results in leakages of fluids and decrease of efficiency of the thermal system. To evaluate the results of deformation during its operation, the temperature distribution of storage materials is calculated by solving a simplified model. In this developed method, the effect of dimensionless parameters on the temperature distribution of rotary air preheater was investigated and compared with the results of modified heat transfer coefficient method. By solving coordination, structural and geometrical equations, and boundary condition in thermal-elastic theory, the thermal stress distributions in rotary air preheater are obtained in an analytical method. Experimental results are obtained by employing factorial design values of rotary air preheater for the validation of the calculation data. Good agreement has been yielded by comparing the analytical data and experimental data. Therefore, some conclusions necessary to undertake an adequate adjustment of thermal stress deformation have also been formulated, and online monitoring of the clearance of radial seals is proposed.