This paper explores the application of artificial intelligence (AI) techniques in the financial sector, with a particular focus on the role of generative Adversarial networks (GANs) in defending against automated attacks in the financial sector. AI technology is regarded as the fundamental technology of the fourth Industrial revolution, and its applications cover robotics, speech recognition, image recognition, natural language processing and other fields. In the financial sector, AI technology has improved business efficiency and accuracy by developing terminal programs with business operation skills that partially or completely replace manual labor. A generative adversarial network is a system of generators and discriminators that generate realistic fake data to help financial institutions identify fraud. Therefore, it is suggested that websites should not only abandon the traditional verification code, but also find other more secure verification methods, and consider introducing a verification system with the ability to generate counter-network to improve the accuracy and security of authentication.