Objective To quantitatively and comprehensively measure the fried food brittleness, to study the changing law of potato chip brittleness during the frying process, and to optimize the frying process of potato chips.Methods A food brittleness mechanical-acoustic emission comprehensive measurement device is employed to measure the brittleness of fried potato chips, taking the maximum mechanical compressive stress measured by the texture analyzer and the maximum acoustic emission energy detected by the acoustic emission instrument as the index parameters. Additionally, the changing law of potato chip brittleness during the frying process is investigated, while single-factor test and response surface optimization are used in search of the optimal process conditions for frying.Results During potato chip frying, the maximum mechanical compressive stress and the maximum acoustic emission energy increase slightly at the moisture content of 80% to 22% and then increase rapidly at the moisture content of 22% to 7%. Then, the maximum mechanical compressive stress increases rapidly with the decrease of moisture content, while the maximum acoustic emission energy remains unchanged. The optimal frying conditions are a frying temperature of 160 ℃, a frying time of 21 min, and a slice thickness of 1 mm, under which the maximum mechanical compressive stress and the maximum acoustic emission energy are 17.13 N and 0.154 mV·s, respectively.Conclusion The mechanical-acoustic emission compressive detection method can be used for fried food brittleness measurement and frying process optimization.