Using purple sweet potato as material, the effects were evaluated, including microwave power, microwave treatment time, vacuum degree, ratio of liquid to solid and gelatin addition on sugar permeability of purple sweet potato under low concentration sugar condition. Response surface methodology was used to determine the five process parameters based on reducing sugar content in purple sweet potato preserved fruit. Results showed that the optimal process conditions were liquid-material ratio of 7∶1 (g/g) (the gelatin content of 1.0%, ratio of maltose sugar to sucrose of 35∶5, and maltose sugar and sucrose concentration of 20%, respectively), microwave power of 560 W, microwave treatment time of 7 min, and vacuum degree of 0.05 MPa. At this optimum point, reducing sugar content and anthocyanin retention rate were found to be 3.60 mg/g and 93%, respectively, and the obtained reserved purple sweet potato had the best sensory quality.