With the continuous development of Internet technology, university English teaching platforms, while providing efficient and convenient teaching and learning methods, are also facing increasingly severe network security challenges. Among them, data leakage and network attacks have seriously affected the normal operation and information security of the teaching platform. In this regard, this paper discusses the optimization strategy of the defense system of the college English teaching platform from the perspective of network security. To address the problem of easy data leakage on the teaching platform, this paper first proposes the “one level of ownership, two levels of management” model, which realizes the strict control of data by the platform administrator. Secondly, the RSA key is introduced, along with its generation algorithm and the AES encryption algorithm, to construct the RSA-AES hybrid encryption algorithm in this paper. Finally, the algorithm in this paper is tested multiple times. In the defense experiment, the platform defense system that uses this paper’s algorithm can identify genuine user requests. In comparison to other algorithms, the average detection delay of this paper’s algorithm is 20 milliseconds, which can effectively resist external attacks. The optimization of this paper’s algorithm for the defense system of a university English teaching platform has been verified, so that it can be stable and sustainable in the information age.