The present invention relates to an ionic phosphorescent metal complex and its preparation method and application. The structure of the complex is: [PtM 3 {(PPh 2 CH 2 ) 3 P}(C≡CR)}(C≡CR’)(μ‑Cl)] 2+ A n‑ 2 / n ; wherein, M is selected from Au (I) or Ag (I); R, R' the same or different, independently selected from: alkyl, alkenyl, alkynyl, aryl, heteroaryl; the alkyl Base, alkenyl, alkynyl, aryl, heteroaryl can be substituted by one or more substituents selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, amino, halogen, haloalkane radical, aryl, heteroaryl; said substituent is optionally further substituted by one or more of the following groups: alkyl, alkoxyl, amino, halogen, haloalkyl, aryl, heteroaryl; A n‑ is a monovalent or divalent anion, n is 1 or 2; μ‑represents a bridge. The organic light-emitting diode prepared by using the complex as the dopant of the light-emitting layer has an external quantum efficiency greater than 10%, and can be applied in the fields of flat panel display and daily lighting.