As a fluid distribution device, the dividing manifold is widely used in engineering systems such as air supply ducts, heat exchangers, and large bag filters. The flow distribution uniformity of the dividing manifold directly affects the overall performance of the system. A geometric model of dividing manifold was proposed to prevent dust accumulating with consideration of the problem of preventing dust and particles from accumulating in dust-containing airflow in practical engineering. With the aim of providing theoretical guidance and basis for the design of shunt manifold, the numerical simulation study on the fluid distribution performance of dividing manifolds with different main pipe shapes and area ratios was carried out to obtain the optimal flow distribution uniformity of the dividing manifold. The effects of Re, main pipe shape and area ratio (AR) on the flow distribution performance of the dividing manifold were analyzed. The results showed that at high Reynolds number, the flow distribution uniformity of dividing manifold was hardly affected by the inlet Reynolds number. When the inlet Reynolds number and area ratio remained unchanged, the flow distribution uniformity of the manifold with a triangular main pipe shape was obviously better than that of the other two main pipe shapes. As the increase of area ratio of the dividing manifold, the flow distribution uniformity index U of the dividing manifold generally decreased. When the area ratio was greater than 1.0, the flow distribution uniformity of all dividing manifolds was decreased. When the area ratio was between 0.8 and 1.0, the flow distribution uniformity index of dividing manifold did not change significantly.