The invention discloses a preparation method and application of a particle uniformly-coated heterojunction type photo-catalytic material. The method comprises the following steps of: proportioning Ta, Ta2O5 or TaON serving as a core according to a mass ratio of 0.001:(1-1):1; adding into an organic solvent in which tantalum halide is dissolved; uniformly wrapping and dispersing on the surface of the core to form a heterojunction precursor by using liquid tension; adding into ammonia liquid solution of Na or K; performing in-situ reduction reaction by taking the heterojunction precursor and alkaline metal as reaction raw materials to form a Ta3N5 wrapped heterojunction photo-catalyst; and finally, thermally treating the heterojunction photo-catalyst at the temperature of 600-900 DEG C. Therate of decomposing water and degrading pollutant by the prepared nano heterojunction structure visible light photo-catalytic material is obviously increased. The prepared Ta3N5 particle uniformly-coated heterojunction photo-catalyst responding to visible light has higher light quantum conversion efficiency, is used for solar conversion and utilization as well as environmental improvement, and has excellent application prospect and economic benefit in aspects of hydrogen making by water photolysis, air purification, water treatment and the like.