Three dimensional integrated circuit (3-D IC) technique has various of benefits compared to traditional two dimensional IC (2D-IC) such as shorter global interconnect and higher performance. Positions of module blocks and Through-Silicon-Vias(TSV) plays an important role in total wirelength. To reduce the total wirelength, we use an iterative white space redistribution algorithm to improve the global interconnect. Constraint graph is constructed and updated during each refinement step, the whitespace redistribution is formulated as two linear programs and solved by an state-of-the-art optimizer. The experimental result shows the algorithm can achieve at most 7.3% wirelength reduction over all testcases and the runtime is very fast.