Operating intraoral scanner capable of constructing accurate dental model and method thereof

A method of operating an intraoral scanner. The intraoral scanner includes an image capturing device and a processor. The method includes the image capturing device sequentially capturing M images along a first dental arch, the processor establishing a first arch model of the first dental arch according to the M images, the image capturing device sequentially capturing N images along a straight-line path from a first anchor to a second anchor on the first dental arch, the processor generating first coordinates of the first anchor and second coordinates of the second anchor according to the N images, and the processor calibrating the first arch model according to the first coordinates and the second coordinates. The first anchor is located at one side of a dental midline of the first dental arch. The second anchor is located at the other side of the dental midline of the first dental arch.