Primary insomnia (PI), a prevalent sleep disorder, has been associated with cognitive deficits and emotional disorders. Several studies have shown that PI involves a wide range of brain abnormalities. In recent years, functional magnetic resonance imaging techniques combined with different analysis methods are widely applied in the study of PI. It can objectively and indirectly analyze the changes in brain functional activities, help to elucidate the neuropathological mechanisms of PI, and provide reliable objective basis for the early diagnosis of disease. In this paper, we reviewed the application of task state functional magnetic resonance imaging, resting-state functional magnetic resonance imaging and function connectivity in patients with PI.