The invention discloses a control method and a controller for 3D (three-dimension) printing and scanning. The method includes the following steps: according to the area overlapping of an upper printed or scanned layer and a lower printed or scanned layer in neighborhood, overlapped areas and a layer difference area are divided out, the overlapped area is first printed or scanned and the layer difference area is then printed or scanned in the same printed or scanned layer, and moreover, printing or scanning power is relatively decreased in the layer difference area, and is relatively increased in the overlapped area; the outlines of the overlapped areas are detected, the overlapped areas are divided into outline areas and filled areas, during operation, the outline areas are first printed or scanned once, the filled areas are printed or scanned once again, the outline areas are printed or scanned once again in the end, the outline of the layer difference layer is detected, the layer difference layer is also divided into an outline area and a filled area, during operation, the outline area is first printed or scanned once, the filled area is printed or scanned once again, and the outline area is printed or scanned once again in the end. The solution is structurally simple, and is easy to implement, and printing and scanning effects are good.