Mulberry fruits were semi-dried using hot air (60-100℃) or cool air (20-40℃), and the effects of the dryingtemperature and processing time on the quality of the final driedmulberry fruits were investigated. Response surface methodologywas employed to establish a statistical model and predict theconditions resulting in minimal loss of the total phenolic content(TPC) and ascorbic acid. Thus, using overlapped contour plots,the optimal conditions for producing semi-dried mulberry fruits,which reduced the moisture residue to 45% and minimized thenutrient losses of TPC and ascorbic acid, were determined for thehot-air process (60.7℃ for 5.4h) and cool-air process (34.8℃ for23.3h). Plus, a higher drying temperature was found to lead to afaster loss of moisture and ascorbic acid, while the TPC wassignificantly decreased in the cool-air dried mulberry fruits due tothe higher activity of polyphenol oxidase between 30 and 40℃.