The regional network border describes the topological border nodes in cyberspace among countries and regions in the real world. By combining active and passive measurement techniques, this paper proposes a dual-stage method of discovering regional network border nodes——RNB. The first stage is to discover the regional network border's candidate sets by using directed topology measurement and multi-source geolocation; the second stage is to accurately identify border nodes from the candidate sets by using multi-source information weighted geolocation and dual PING geolocation. The experiment took mainland China as the target region and discovered 1,644 border nodes. Compared with the CAIDA data set, our results have 37% of exclusively discovered border nodes with only 2.5% of the measurement cost. The accuracy rate under manual verification is 99.3%, and that under the verification of an ISP operator is 75%.