The invention discloses a paint composition for plastic. The paint composition comprises a component A and a component B. The component A comprises organic silazane resin, a fluoro-silane coupling agent, and perfluoro-alkane. The component B comprises polyisocyanate resin and 4,4-trimethylenebis(1-methylpiperidine). The invention further discloses a preparation method of the paint composition, an application of the paint composition on the external surface of automobile lampshade, and a coating prepared therefrom. The provided paint composition has the advantages that through the cooperation between organic silazane and the fluoro-silane coupling agent, the coating, which is formed through a curing and crosslinking mode, has extremely high bond energy; moreover, no free radical exists, the surface energy is extremely low, at the same time, the light loss rate and yellowing rate are extremely low, the paint is easy to wash during the using process, the flexibility of the coating is improved, and the performance on resisting the impact of stones is excellent.