Digital therapy shows promise in providing precise assessments and enhancing the efficacy of treatments for mental illness, offering advantages such as convenience, flexibility, and the potential to reduce costs by shifting towards preventive care. This article reviews the development and benefits of digital therapy in mental health care and discusses the challenges it faces, including concerns over privacy, ethics, security, accessibility issues, digital divides, and the lack of sufficient clinical validation and standardization. It also highlights specific risks to mental health patients and explores potential future developments such as integration with brain-computer interfaces and neurofeedback, the use of robot therapists based on large language models, applications of virtual reality or the metaverse, and combinations with traditional physical treatments and medications. The author calls for urgent policy recommendations to refine regulations, establish unified evidence standards, enhance training and education for healthcare providers and patients, and to build multidisciplinary collaborative mechanisms to advance personalized and effective digital therapy in mental health.