The invention discloses a production method for modified casein. Qula casein is directly used as a raw material and is puffed through an extruder to produce the modified casein, so that the wire drawing property of the qula casein is effectively improved and is doubled, so that the standard of fresh milk casein is basically met. The emulsibility, the dissolving property and the viscosity of the qula casein are enhanced, and the casein production technology and the quality of a product are improved; the problems of low dissolving property, odor of the product and the like of conventional qula casein are solved; meanwhile, the obtained modified casein product is high in viscosity and high in flowability; the product has a bright color, smells normally, is crystalline, has a good dissolving characteristic, and can meet a high product quality standard; all physical and chemical indexes such as proteins, fat and ash meet the standard.