T-pipe is a common component in high-pressure manifolds, which are in high-pressure environments while subjected to solid particles erosion for a long term, which subsequently affects the safe operation of the relevant system and the service life of pipelines. Herein, the erosion behavior of the high-pressure tee manifold was assessed via a home-made liquid-solid two-phase erosion test bench, which can apply dynamic load on the tested t-pipe subjected to erosion. A model was proposed for description of erosion under dynamic load, and then coupled with a numerical simulation software, to analyze the erosion performance of tee structures at various spatial angles under different internal pressures, velocities, and particle mass flows. Results show that the maximum erosion rate of different tee structures increases with the increase of internal pressure, exponentially with the increase of flow rate, linearly with the increase of particle mass flow rate, and the greater the tee space angle, the faster the growth rate. When the space angle of the tee structure increases, the maximum erosion rate increases, while the erosion performance does not change with the change of internal pressure, velocity, and particle mass flow rate. The results can provide reference for the safe operation of the high-pressure tee manifold.