In the workflow of image reproduction, the halftone image is usually used as scanned original image. The moiré patterns are a result of intervention during the process of scanning. This paper provides a descreening method of scanned halftone image based on wavelet according to the cause and the character of moiré patterns. Experiment result shows that this descreening method can remove the moiré patterns effectively and at the same time hold the definition and entropy of the scanned halftone image.