Abstract: The technology has described the basic theory and implementation of assaying the major component density in cowmilk by using the combination of ultrasonic and electronic parameters. It has discussed the assaying methods of ultrasonic naturalparameter in cow milk especially. At the meantime, it has described the building methods of predictive model essential in the entireassay system. Finally, it has compared both ultrasonic and parametric methods. The result shows that ultrasonic method has gotsome advantages like stableness, correctness and quickness. The coefficient of variation for repeatability in assay is less than0.02 and the relative accuracy is less than 2%. It only takes 30 seconds to test each sample. It can fully meet the demands of practicalassay. The research provides a new method of no-wear fast assay for dairy products.

Key words:  , milk components； ultrasonic； fast measurement； least square； multivariate regression；