Abstract: The absolute measurement of laser power mainly adopts an electrical calibration laser power measurement system, which traces the laser power to the voltage and standard resistance reference to achieve the value realization. For absolute measurement of high power lasers of 10,000 watts level, the damage resistance of the absorber is the key to the measurement system. In this paper, the design and damage-resistant performance of an absorber of 10 kW electrical substitute laser power meter were studied, and the damage-resistant laser absorber cavity was designed and developed based on the reflective beam expander structure and water cooling method. The heat transfer characteristics of the absorber under different laser power, spot size, and cooling water flow rates were studied using numerical heat transfer analysis. The results show that the temperature rise of the laser absorption surface is well controlled, and the upper limit of the power measurement of the absorber reaches 15 kW, which is mainly limited by the vaporization of cooling water caused by the surface temperature rise of the water cooling channel. The results of the numerical analysis are essential for the clarification of the damage resistance, the setting of the measurement system parameters, and the optimization of the absorber structure. Under the condition of a high-power laser, the electrical calibration measurement system with the absorber was tested. The maximum measurement power reached 14.3 kW, and the measurement data remained stable at different powers without damage to the absorber.