Abstract: With the rapid development of big data technology, security hidden risk prior awareness technology based on big data technology is becoming more and more mature, which provides an effective means for analyzing massive data and mining accident rules. This paper optimized and improved the classical Apriori algorithm in data mining technology, based on the improved Apriori algorithm, proposed a railway network security early warning method, and combined with the requirements of network security level protection, constructed the railway network security index system. The correctness and availability of the algorithm were verified by simulation experiments. The research shows that the improved Apriori algorithm can implement the railway network security hidden risk prior awareness and effectively solve the problem of the lack of early warning and prevention means, which has a certain application value in railway network security early warning.