Abstract: The structure of vascular network in solid tumor is extremely disordered and non-uniformed. These characteristics result in the complexity and diversity of the blood flow in tumor microcirculation which eventually make drug delivery and targeted therapy difficult in solid tumor. In order to investigate the influence of tumor microvascular network on the blood flow, a vertical interconnected micro-network channel was fabricated by soft lithographical method in this work, designed to simulate the expanding, multi-branched and multi-interconnected tumor vascular network. Employing the micro-flow-system, the red blood cell (RBC) suspension was injected into micro network channel at a certain speed. Inverted microscope was used to observe the migration of RBCs and the sequential images were recorded. PIV-lab package of Matlab and the tool box of the high-speed video camera were used to process the image data. The results show that, hemotocrit (Hct) level of RBC suspension is the main factor to affect the flow and distribution of RBCs in the micro-network. The trajectories of RBCs in the micro-network vary with different Hcts. When Hct level is as low as 1%, the RBCs in the micro-network flow only along the axial direction of the channels, while Hct level becomes higher, some RBCs will flow across the radial channel and the two types of RBC flow trajectories appeared. Furthermore, at the same inlet flow rate, the speeds of RBCs in the micro-network show difference with different Hct levels. The velocities of RBCs with 3% and 5% Hct levels are evidently higher than those of RBCs with 1% Hct level.