Abstract: A 3D printing device is provided. The 3D printing device is adapted to print a 3D object including a plurality of layer objects. The 3D printing device includes a weight sensor, which is configured to measure an actual weight value of the layer objects formed on a carrying surface or configured to measure an actual weight value of a feed tray. A controller of the 3D printing device estimates an ideal weight value corresponding to a first layer object according to a printing sequence of the first layer object in the layer objects. The controller receives the actual weight value corresponding to the first layer object from the weight sensor, and compares the ideal weight value with the actual weight value to determine whether printing abnormity is occurred. According to the disclosure, the printing quality of the 3D printing device is improved.