Abstract: Abstract: The by-products from industrial cultivated pleurotus eryngii usually include off-normal fruit body, fruit cap/foot of mushroom. With commercial quality classify, the amount of by-products of the mushroom is about 20% of total yield. These by-products are low in their commercial price although with same nutritive quality as commodity fresh mushroom. In order to promote the profitability of industrial cultivation of pleurotus eryngii, the processing technology to make use of the by-products was proposed for a value added instant mushroom snack. During the processing, it is found the dehydration technology has important influences on product qualities, such as moisture content, texture, sensory quality. A conventional dehydration procedure used for this product is the hot-air drying, which has advantages in easy for operation and low investment for facility, but concomitant with difficulty in quality control of products, especially in moisture content and sensory quality. By adding vacuum drying procedure, this study aimed to improve the control effect of hot-air drying on moisture loss of products. The dehydration of hot-air drying was conducted and aided with vacuum drying procedure, and the technical parameters were optimized by response surface method. The model was obtained quadratic general rotation design experiments with three factors at five levels. The three factors of hot-air drying temperature (X1), hot-air drying time (X2) and vacuum drying temperature (X3) at five levels were used in model optimization and quadratic general rotation design experiment. The effects of drying methods on drying rate, light intensity of colors, product texture and sensory scored were evaluated comprehensively. In addition, the products prepared by three methods of hot-air drying, vacuum drying and hot-air drying aided with vacuum procedure were compared respectively for their quality indexes including sensory evaluation, the color, brightness and texture. The drying rate and unit energy consumption of three drying methods were also analyzed. The results showed that the temperature was a significant influencing factor in drying process (P＜0.01) for both hot air drying and vacuum drying procedures. The significant degree of three factors was in order as the temperature in vacuum drying (X2, P＜0.01) > temperature in hot air drying (X1, P＜0.01) > hot air drying time (X3, P＜0.05), respectively. The optimum parameter was: for hot air drying at 60℃ for 20 min (the moisture content of product ≤ 78%), vacuum drying at 55℃ under -0.09 MPa, respectively. With the optimum parameters of the factors, the data from model prediction and verification testing indicated that the absolute error between the value of prediction and experiment testing was less than 5% with no statistical significance (P>0.1). Moreover, the quality of dehydrated instant mushroom snacks with improved dehydration technology was higher in contrast with that by hot-air or vacuum dried products. The improved dehydration technology can also raise the drying rate and save 57% energy consumption compared with that of vacuum drying process. The research can provide a theoretical basis for further study on processing technology of instant pleurotus eryngii snacks.