The invention relates to range hood cookers, in particular to a 
hearth plate of a totally-closed air curtain range hood. The four sides of the 
hearth plate are provided with angle-adjustable strip-shaped air outlets; and by means of the 
hearth plate of the totally-closed air curtain range hood, a totally-closed tapered air curtain can be formed, cooking fumes can be totally closed in the tapered air curtain, and the cooling fumes are conveyed to a suction port of a range hood along with the tapered air curtain and discharged out of a kitchen completely through the range hood. The hearth plateof the totally-closed air curtain range hood comprises a hearth plate body, a draught fan, a 
noise elimination plenum chamber, angle-adjustable strip-shaped air outlets, the range hood, the totally-closed tapered air curtain, an air-input grille, an 
airflow-stabilizing grille and a steel wire 
safety net. The hearth plate of the totally-closed air curtain range hood is characterized in that angle-adjustable strip-shaped air outlets are formed in the hearth plate body; air enters through the air-input grille and is conveyed by utilization of the draught fan; and then the air passes through the 
airflow-stabilizing grille, enters the 
noise elimination plenum chamber and is discharged from the angle-adjustable strip-shaped air outlets, and the totally-closed tapered air curtain is formed. The angle-adjustable strip-shaped air outlets are provided with corresponding air output angles, and a beveled air curtain is formed by the air discharged. A closed rectangular 
pyramid is formed by air curtains on four sides and the range hood; the cooling fumes are discharged out of the kitchen completely through the range hood; and 
pollution of the kitchen by the cooling fumes and damage to human bodies by the cooling fumes are completely isolated.