Transcranial alternating current stimulation is a non-invasive form of brain stimulation that can use sinusoidal and bipolar alternating currents to stimulate cortical neurons， regulate endogenous brain oscillations， and induce synaptic plasticity changes， help to relieve symptoms such as depression， anxiety， delusions， and dementia. This article reviews its clinical application and mechanism in depression， schizophrenia， and other diseases to help us understand the progress and deficiency of current research， and provide some hints for future clinical application.