LLMs face content security risks such as prompt information injection, insecure output processing, sensitive information leakage, and over-dependence, etc. By constructing a firewall for LLMs with intelligent detection strategies and introducing multi-engine detection capabilities such as rule matching, semantic computing, and AI models, we can intelligently detect and dispose of inputs and outputs of the LLMs, and realize the full-time on-line security protection of LLM applications. The system is tested on open-source LLMs, and there is a significant improvement in terms of the detection rate of insecure content.