Multi-threshold CMOS (MTCMOS) is an e.ective power-gating technique to reduce IC's leakage power consumption by turning off idle devices with MTCMOS switches. However, few existing literatures have discussed the algorithms required in MTCMOS's back-end tools. In this paper, we propose a switch-routing framework which serially connects the MTCMOS switches without violating the Manhattan-distance constraint. The proposed switch-routing framework can simultaneously maximize the number of MTCMOS switches covered by its trunk path and minimize the total path length. The experimental result based on four industrial MTCMOS designs demonstrates the effectiveness and effciency of the proposed framework compared to a solution provided by an EDA vendor and an advanced TSP solver.