The invention relates to a quadridentate platinum (II) complex and application. The complex has an N^N^N^O configuration, and a structure of the complex is as shown in a formula (3), wherein A1-A5 aresubstituted or non-substituted five-membered rings, six-membered rings and fused ring structures. The complex can be applied in the field of OLED as a phosphorescent dopant material. The platinum (II) complex has high fluorescence quantum efficiency, good thermal stability and a low quenching coefficient, and can be used for producing orange-red light OLED devices with high luminous efficiency and low roll-off.