A scanning module of an image scanner for scanning a document is provided. The scanning module of the image scanner includes a base, a reflective mirror stand, a shaft, a reflective mirror member and a gear set. The reflective mirror stand is mounted on the base. The shaft is rotatably mounted on the reflective mirror stand. The reflective mirror member is fixed on the shaft and rotated with the shaft. The gear set is pivotally coupled to the shaft for rotating and driving the shaft to adjust the reflective angle of the reflective mirror member, which is fixed on the shaft.