To measure accurately the spatial and temporal distribution of laser intensity in a far-field for a mid-infrared high energy laser system, two thermal issues existing in laser parameter measurement for an uncooled photoconductive HgCdTe detector were discussed, including environmental temperature variation and the laser induced temperature rise of a sensor chip. Then, two solution schemes were presented respectively. On the basis of empirical formulas for electrical properties of n-type HgCdTe materials and device physics of the photoconductor, the temperature dependences on dark resistance and responsivity were analyzed. A thermal analysis model of the photoconductive HgCdTe detector was established and verified by experimental data. Thermal contact resistance and natural convection were considered in this model. After the time characteristics of thermal equilibrium between sensor chip and environment were investigated, an environmental temperature calibration model for continuous wave laser parameter measurement was presented. Finally, dynamic responses of the HgCdTe detector under fixed and variational laser irradiations were analyzed, and a correcting method for the effect of laser heating on sensor chip was presented. The results show that the measurement uncertainty of a single unit in the beam detector array is reduced by 2% or more under a typical implementing condition. The proposed methods have been successfully used in different mid-infrared high energy laser quantificational measurement systems.