The invention relates to a process for the production of well-preserving lactose-free and low-lactose milk products, wherein sugars and proteins in a milk raw material or milk and whey raw material mixture are separated into a sugar fraction and a protein fraction by ultrafiltration； at least the protein fraction obtained as ultrafiltration retentate is thermally treated at a temperature ranging from 60°C to 80°C for 10 minutes to 10 hours to inactivate the natural plasmin enzyme system and other harmful enzymes therein； the thermally treated protein fraction and the sugar fraction are heat treated； and the milk product is composed from the heat-treated protein fraction and from optional other preparation components into a milk product with a desired composition and sweetness.
