Production method of Zn-Al-Mg coating steel plate with high coating hardness and coating steel plate

The invention provides a production method of a Zn-Al-Mg coating steel plate with high coating hardness and a coating steel plate. The steel plate is cooled to room temperature at the cooling speed of 10-50 DEG C/s after being subjected to continuous annealing and hot dipping, and then is subjected to double cold rolling; the deformation rate of the coating steel plate is 5%-50%; the deformation rate of the coating is 7%-40%; the thickness of the steel plate before hot dipping is 0.3-2.0mm; the thickness of the Zn-Al-Mg coating subjected to hot dipping is 15-30 microns; the thickness of the coating subjected to double cold rolling is 10-29 microns; the thickness of the coating steel plate is 0.3-2.0mm; the thickness of the coating is 10-29 microns; the hardness of the coating is Hv120-Hv200; the scratch resistance of the coating is improved; meanwhile, the application range of a hard steel plate can be met; and the coated steel plate is suitable for the surface machining requirements.