Purpose/Significance To build a network security platform based on the software defined networking (SDN) architecture, and to enhance the security protection of hospital cloud computing. Method/Process A network security platform is built based on the SDN architecture and is linked with the intrusion detection system to form an active defense system. By comparing and analyzing the number of tenant horizontal attacks, the success rate of attacks, the number of unobstructed businesses by strategies, the volume of data encrypted by ransomware, and the operating hours of the security team before and after the application of the platform, the effectiveness of the platform is verified. Result/Conclusion The network security platform based on SDN architecture can effectively identify and block malicious traffic, and enhance the security protection for hospital cloud computing.