With the widely use of IP network and the continuing increase of the bandwidth of the network, more and more applications based on the IP technology are created, Such as VoIP,P2P and IPTV etc.. Many of them have been deployed into our life and give us much convenience. However, some problems still need to be resolved to make them perform better. How to efficiently traverse the firewall/NAT is one of the obstacles.This thesis mainly introduces a new type of firewall/NAT traversal solution, which uses different traverse methods in different network environments. There are mainly three parts in it:In the first part (chapter 1 and 2), technical background knowledge of some kinds IP applications and firewall/NAT are presented to explain the issue of the problem.In the following part 2, the principles of the existing techniques in the same field are described,analyzed and compared in details in the third chapter. In succession, the central ideal of the traversal solution are highlighted in the fourth chapter: inspiring from some good ideas of the existing techniques, the traversing process are optimized by doing a firewall/NAT test first and then choosing the most reasonable traversal method according to the test result. In the last chapter of this part, the firewall/NAT traversal solution's software design for the SIP and P2P applications are explored, together with part of the realization for firewall/NAT in the field of SIP application.In the last part of this thesis, the software test result of the SIP application's firewall/NAT traversal solution and a prospect of the related research field are presented.