Network on chip (NoC) is an emerging area and recognized as the future methodology for chip design. Provision of QoS in network on chip is a challenging problem and receives much attention recently. A QoS routing scheme is proposed to support various traffic with different QoS requirements in the interconnection networks of NoC. Specifically, three distributed QoS routing algorithms are developed based on different blocking handling methods. The algorithms use local information and are proven to be deadlock free and livelock free. Various strategies to handle blocking are utilized to lower the call failure rate. Simulations are carried on 3D torus topology. The results show that the proposed algorithms increase the network capacity by 30-40% (compared with the dimension order algorithm) and by 20-30% (compared with Duato's algorithm).