A new type of tapered manifold is proposed aiming at the problem of flow maldistribution in the flow channels of the traditional plate heat exchangers. According to the position of the tapered manifold, it was divided into three cases: inlet arrangement, outlet arrangement, inlet and outlet arrangement. Through the three-dimensional numerical simulation, the flow distribution characteristics, flow uniformity and total pressure drop were studied. The flow uniformity of the heat exchanger was evaluated by the relative standard deviation. The results show that there is a vortex zone at the end of the inlet manifold of the traditional plate heat exchanger, and the inlet arrangement of the tapered manifold avoids the generation of the eddy current zone. Compared with the traditional plate heat exchanger, the relative standard deviationof the new U-in plate heat exchanger is reduced by 16.7%~28.7%, and the pressure drop is reduced by 2.6%~6.5%.