The present invention discloses a class of four-dentate ring metal platinum (II) phosphorescent luminescent material as shown in formula (I): wherein, the five-membered heteroaromatic group Ar is selected from one of the following: 2H-1, 2,3‑triazole where X 1 =N,X 2 =N,X 3 =CH); 1H-1,2,3-triazole wherein, X 1 =CH,X 2 =N,X 3 = N; 1,3,4-oxadiazole wherein, X 1 =O,X 2 =C,X 3 = N; oxazole wherein, X 1 =O,X 2 =C,X 3 =CH or thiazole wherein, X 1 =S,X 2 =C,X 3 =CH. The application of one or two or more of the four-ring metal platinum (II) phosphorescent luminescent materials in the present invention as a light-emitting layer of an organic light-emitting device. The four-ring metal platinum (II) phosphorescent luminescent material of the present invention has strong molecular rigidity, can effectively reduce the energy consumed by molecular vibration, has high phosphorescent quantum efficiency, and has good chemical stability and thermal stability.