Cognitive radio can improve the spectrum utilization by making use of spectrum holes in time and space dimension. The routing protocol in cognitive radio is different from traditional routing protocols as the secondary users can not interfere with the primary users both in time and space. In cognitive ad hoc networks，interference is chosen as routing metric，and it is divided into intra-system interference and inter system interference. Based on existing ad hoc interference routing protocol，its interference weights are improved，and new routing protocols are proposed in order to minimize inter system interference and the joint interference of intra-system and inter system. The simulation result shows that the proposed routing protocols are proved to well capture the route performance in the context of cognitive ad hoc networks.