Abstract: To address the difficulty in accurately evaluating the instantaneous impact force magnitude and unsticking effectiveness of drilling jars during jarring and unsticking operations in deep and ultra-deep wells, an impact force acquisition sub suitable for high-temperature high-pressure environments in ultra-deep wells was developed with a ϕ121.0 mm drilling jar as an example. Its main functional components included resistance strain gauges, an integrated circuit board, a battery component, a shock-absorbing device, a temperature sensor, and a pressure sensor. The sub has a total length of 1 100.0 mm, an outer diameter of 127.0 mm, a rated operating temperature of 150 °C, and a compressive strength of 75 MPa, with resistance strain gauges employed as the sensing elements. During service, the sub can automatically switch between high- and low-frequency acquisition modes through the coordinated triggering of temperature, pressure, and acceleration sensors, thereby meeting the impact force acquisition requirements in long-term downhole operating environments. Through finite element strength check, simulated well tests, and surface bench tests, the strength reliability, sealing integrity, and acquisition stability of the sub under high-temperature high-pressure conditions were validated. It can accurately capture axial load fluctuations in the drill string during jarring and unsticking, providing a direct and reliable measurement means for quantitatively evaluating the jarring performance of drilling jars.