A three-dimension (3-D) printing method and a 3-D printing system are provided. The method includes: generating printing information according to model information of a 3-D object; controlling a 3-D printing apparatus to perform a 3-D printing operation, so as to print a supporting object and the 3-D object, wherein the supporting object is used to support the 3-D object. Furthermore, the step of generating the printing information includes: detecting a floating contour of the 3-D object on the first printing layer according to the model information; and removing printing information of the supporting object from printing information corresponding to a second printing layer according to the floating contour. Thereby, difficulty of removing the supporting object can be reduced.