The invention discloses a paint spraying assistant device, belonging to one field of paint spraying technology. In order to reduce the consumption of diluents during a paint spraying process and make a surface onto which paint is sprayed smooth and bright, the paint spraying assistant device adopts the following technical measures: a workpiece onto which paint is to be sprayed is connected with a mechanical vibration device, paint drops are flattened and blended together via mechanical vibration during a paint spraying process, and thus a painted surface is further smooth and bright. Different from a method of making a painted surface smooth and bright via a great quantity of diluents, the measures provided by the invention have the advantages that the workpiece onto which paint is to be sprayed generates mechanical vibration via a physical method, and the mechanical vibration breaks a granular balance structure of the paint drops on the workpiece, so that the paint drops collapse and disperse, are blended together and then are attached to the surface of the workpiece better. The paint spraying assistant device has the effect that a painted surface can be further smooth and bright even when paint is relatively thick, the consumption of the diluents is reduced, and the environment pollution is alleviated.