Cryptographic card is a kind of encryption device located in the physical layer of the network security platform. It provides several encryption and decryption algorithms, digital signature, and other cryptographic operation services for application systems. Considering the security of cloud computing, the cryptographic card needs to be high speed and achieve high concurrency through virtualization technology. The challenge for the cards as input/output (I/O) devices is how to achieve high I/O performance and share I/O devices in the case of virtualization effectively. At present, the development of I/O virtualization technology is lagging behind, which affects the overall performance of the virtual machine. Based on this, this paper realizes the software virtualization cryptographic card by using field-programmable gate array and the single root I/O virtualization technology. In practical applications, a virtualized cryptographic card is built into the server through the peripheral component interconnect express bus, which has high performance and can be shared by many users. The results show that this technology has broad applications in the field of information security.