In the process of anti-interception of information, due to the weak control ability of data nodes, data is easily lost and information security is not high. An anti-interception method of optical fiber communication physical layer based on chaotic mapping is studied. The existence of the intercepted signal is determined by optical fiber signal detection and identification, and the ciphertext matrix is constructed based on the chaotic map encrypted image. The physical layer communication code is jointly transmitted to realize the information exchange between the receiver side and the transmitter side. We establish the anti-interception model of the communication physical layer to achieve the goal of anti-interception of the optical fiber communication physical layer. In the constructure of optical fiber communication network, a set of images with practical significance are selected as test samples. The proposed method and the traditional method are used for comparison. The experimental results show that the image data can be fully encrypted based on the proposed method. It has strong anti-interception performance, and the data information in the image can be retained in the image transmission, However, the traditional method loses 15 groups and 12 groups respectively, indicating that the proposed method has better performances.