Because of complicated security policy collisions and twisted interest conflicts in network domains, inter-domain routing security has been a challenge of secure routing. At present most of related researches focus on the authentication of routing source and true path, but seldom addresses another point of whether the routing decision process matches expected policy. In this paper, a multipath inter-domain routing decision verification protocol was designed, which can verify whether an autonomous domain (AD) keeps its promise about choosing appropriate M from N paths that have the same destination and are received from upstream ADs, and sending to a downstream AD. According to the analysis, the protocol is valid and can protect privacy of participants, as well as can resist attacks such as forgery, modification and replay etc. and deploy on internet incrementally.