The invention relates to graphite-phase carbon and nitrogen compound powder, as well as a preparation method and an application thereof. The powder uses an aromatic multimember heterocyclic ring composed of carbon and nitrogen elements as a repeat unit, and has a layered graphite phase structure. The preparation method of the powder comprises the following steps of: slowly heating an organic small-molecule compound containing carbon and nitrogen elements and other precursors to 450-600 DEG C, reacting at the temperature to form a yellow solid, washing the solid with an acidic solution and drying to obtain a target product. According to the invention, the product is acquired by carrying out a solid phase reaction under normal pressure and using inexpensive and easily available raw materials containing carbon and nitrogen elements as a single molecular precursor, the process is simple, the reaction atmosphere does not need to be adjusted and controlled, the equipment investment is low, the large-scale production can be realized, and the obtained product has multiple optional practical forms and can be widely applied in the industries of air purification, such as sewage treatment, self-cleaning coating, environmental purification including hydrogen preparation through utilizing water photolysis and CO2 photocatalytic reduction and the like, solar energy conversion and utilization, etc.