Face-changing technology is a virtual face transformation technology that combines one person's facial features or expressions with another person's face through computer image processing and artificial intelligence algorithm. The principle of face transformation technology is to extract and match the features of the source image and the target image, and then apply the features of the source image to the target image to make the target image have the appearance features of the source image. This technology has been widely used in entertainment and media fields, such as film production, special effects processing and role replacement. It is also used to make humorous short videos and expression packs. In addition, face-changing technology has also been applied to virtual reality and augmented reality, providing users with a more immersive experience. However, the face-changing technology has also caused some problems and controversies. One of the problems is privacy and security risks. People are worried that their facial features may be abused, such as for fraud, false information dissemination or malicious activities. In addition, the face-changing technology may also be used to deceive the face recognition system, thus posing a threat to security. In a word, face changing technology is a technology to synthesize one person's facial features into another person's face through image processing and artificial intelligence algorithm. It is widely used in entertainment, media, virtual reality and other fields, but it also causes people's concerns about privacy and security.