The aim of the study was to research the opening problem of split type suck-filtration mold for molded pulp packaging products, in order to ensure that the product thickness is uniform, and the appearance was good. Through analyzing the energy loss of the filtrate flowing in the molding process of the molded pulp packaging products, the energy equation of filtrate flowing process in the split type mold was established, to research the relationship of the opening ratio between the specific parts of the mold. Equation for the opening ratio relationship between different parts of the mold was established, and the opening arrangement method in different parts of the mold was studied. In order to ensure uniform thickness of the product, the opening ratio between different parts of the mold need to meet a certain relationship; Cavity bottom should use 60° staggered opening arrangement method, and the vertical wall can be divided into several continuous unit opening areas, using heterogeneous opening arrangement method.