The invention relates to an efficient 
mirror plane flatting agent for 
powder paint, an preparation method and an application. The efficient 
mirror plane flatting agent is prepared from, by 
mass, 600-800 parts of 
acrylic acid butyl ester, 100-360 parts of 
lauryl methacrylate, 20-50 parts of hydroxyl 
acrylate monomers, 20-50 parts of 
styrene, 10-25 parts of azodiisobutyronitrile and 900-1500 parts of methylbenzene. The number-average molecular weight Mn of the prepared flatting agent is 6000-7000, the molecular 
weight distribution PDI is 1.5-2.8, and the flatting agent can be prepared into a 
solid state through gas-phase 
silicon oxide adsorption in the later period. The flatting agent is mainly applied to the 
powder paint, hydroxyl polar groups and 
benzene rings are introduced in the flatting agent, therefore, the compatibility of the flatting agent and resin in the 
powder paint and the wettability of the flatting agent for substrates can be effectively facilitated, and then a 
coating can achieve the excellent flatting, shrinkage cavity resisting and brightening effects; in addition, the Mn of the flatting agent is 6000-7000, the PDI is 1.5-2.8, and therefore the flatting, shrinkage cavity resisting and brightening effects of the 
coating can be further optimized; furthermore, the polar group hydroxyl is introduced, and therefore the 
adhesive force of the 
coating on the 
metal substrates can be effectively improved.