Hole cleaning is an important factor in horizontal drilling; however, there is no generally accepted approach to measure the cuttings distribution downhole in practical drilling applications. This study proposes an approach to evaluate the dynamic downhole cuttings distribution quantitatively by using along-string annular pressure (ASAP) data. The relationships between cuttings distribution and pressure drop are investigated, and a pressure-driven hole cleaning model is developed by inverting the effect of cuttings on wellbore pressure drop for given flow conditions. A hybrid drilling hydraulic model is developed by combining the traditional drilling hydraulic model and a self-tuning approach to accurately calculate wellbore pressure drop without cuttings. The effect of cuttings on pressure drop is obtained by comparing ASAP data and predicted pressure data from the hybrid drilling hydraulic model. Then, the downhole cuttings distribution is obtained by inverting the pressure changes using the pressure-driven hole cleaning model. This work provides an accurate approach to evaluate real-time hole cleaning conditions and detect insufficient hole cleaning problems for real-time drilling activities if wired drillpipe is deployed. It also expands existing analysis techniques for real-time drilling data and provides new methods to make use of the expanded sensor capability from wired drillpipe.