Working principle of the ice cream machine: the ice cream slurry is pumped into the freezing cylinder of the ice cream machine together with air through a mixing pump equipped with an air inlet regulating valve, and is mixed by a stirrer in the ice cream machine; at the same time, the refrigerant in the jacket of the freezing cylinder freezes the slurry, and the ice cream frozen on the inner wall of the freezing cylinder is continuously scraped by a stainless steel blade on the stirrer. The slurry is continuously frozen, scraped, mixed with air and stirred, and finally it is pumped through an adjustable constant pressure valve to become an ice cream product with expansion rate and fine structure.