Abstract: The experiment of parameter for alfalfa drying was done under different experimental conditions, it determines the relationship between parameters and quality of dried alfalfa. It is a basis of further experimental design. The influences of drying temperature, air velocity, initial moisture and drying time on protein content were analyzed with nonlinear regressional orthogonal design. Utilizing analysis method of single-parameter, the relationship between experimental criteria and drying parameters was investigated, and using method of contribution-rate the order of the drying parameters was confirmed and some theoretical basis was provided for designing reasonable drying parameters. Experimental results show that order of factors affecting protein content is initial moisture, drying temperature, drying time and air velocity. And conservation of quality is better under 176.5℃, 0.32 m/s, 79%wb and 3 minutes.