Abstract: This paper deals with the effects of air temperature,air speed and sliced thickness on the mannan content in konjak, drying speed and energy comsuption at 23 different combinations of working conditions with simulating hot ait drying tests for konjak using the design of quadratic-rotation-orthogonality. As a result, a mathematical model which quantitatively explains various properies and three factors for konjak drying was obstained. The model was then studied and analyzed by using multiple-object non-linear optimization theory and the konjak hot air drying parameters for superior quantity, high-level efficiency and energy-saving were reached respectively.