An aided design method of print layers for 3D printing is provided. The method is performed for rendering and displaying a GUI at a computer apparatus, selecting one of print layers, configuring an editable region and marking it on the GUI, configuring one or more print block(s) in the editable region according to an edit operation, generating one of multiple layers of object print data according to the print block(s) and performing above-mentioned steps repeatedly until all of the multiple layers of the object print data have been generated. The present disclosed example has an ability to aid the user to design multiple print layers and reducing a probability of failure of printing 3D physical model.