The automatic Kjeldahl nitrogen analyzer (protein analyzer) is an automatic intelligent measuring instrument designed according to the classical Kjeldahl principle. It should be widely used to test grain and oil foods, dairy products, beverages, feed, soil, fertilizers and drugs. The total content of ammonia nitrogen and protein nitrogen in sediments and chemical products is an important physical and chemical analysis instrument for product quality testing. SKD series automatic Kjeldahl nitrogen analyzer adopts new long-life design, advanced microcomputer intelligent control, LCD color touch screen operation, Chinese function table interface to complete man-machine dialogue operation, automatic completion of acid addition, twisting, and addition of diluent , a series of standardized processes such as distillation, titration, cleaning, storage, printing, etc. Titration is judged by the international standard color method (color sensor), replacing the traditional complex electrode potential method and single-wavelength photoelectric colorimetry. The data is accurate and the performance is stable. There are a number of patents with independent intellectual property rights. Some technologies and structures are first created in China and reach international standards.