Abstract: To address the dilemma of balancing dimensional stability and sintering densification in binder jetting 3D printed (BJ3DP) porous tungsten, this study selected three types of unimodal tungsten powders as raw materials to construct five groups of trimodal powder gradation systems with different blending ratios. The effects of powder gradation on geometric packing, constrained sintering mechanisms, and mechanical properties were systematically investigated. The results show that the equal-ratio (1:1:1) blending system exhibited the most significant geometric packing effect, achieving a maximum green relative density of 64.13%. This effectively suppressed the delamination defects commonly caused by high-specific-surface-area powders, thereby ensuring the integrity of the green bodies. During the high-temperature densification stage, the three-dimensional skeleton synergistically constructed by medium and coarse particles dominated the entire "constrained sintering" process. Its spatial pinning effect restricted the localized high-activity shrinkage of fine powders and controlled the volumetric shrinkage of the matrix to within 6.5%, endowing the components with excellent macroscopic dimensional stability. Simultaneously, fine particles preferentially sintered at the interstices of the skeleton to form a continuous sintering-neck network, which promoted the enhancement of metallurgical bonding strength. The flexural strength of the sample with the optimal gradation reached 114.54 MPa. This study effectively balances the high dimensional accuracy and high mechanical strength of porous tungsten components, providing an important theoretical basis and technical support for the precise fabrication of high-performance refractory metal porous structures.