In a high-power Pr:YLF solid-state laser, the thermal effect of gain medium is one of the prime limiting factors, and its thermal damage has become the major concern. The thermal effect of Pr:YLF crystal was analyzed theoretically, and the distribution of temperature, thermal stress, thermal focal length, and pump polarization effects of the Pr:YLF crystal were simulated. The thermal effect investigation indicates that under reasonable pumping power density, crystal length, and beam waist size and location, the temperature rise and nonuniformity of thermal distortion are not intensified under high-power operation. Additionally, the relationship between Gauss or Super-Gaussian pump mode and thermal focal length of Pr:YLF crystal was simulated. To the best of our knowledge, this analysis is the first to examine the thermal effect of Pr:YLF crystal for power scaling, and this thermal effect investigation of Pr:YLF crystal provides first-hand data for a high-power, visible, solid-state laser that could be helpful for high-power Pr:YLF solid-state laser design.