1. A method for printing a 3D object and searching a plane of a 3D model, using an editing software executed in a computing device, the method comprising: a) importing a first 3D model data and opening a first 3D model according to the first 3D model data at the computing device; b) obtaining an outline of the first 3D model at the computing device; c) obtaining coordinate information of a plurality of coordinate points within the outline at the computing device; d) setting one of three axes of the first 3D model to be a datum axis at the computing device; e) setting a lowest point of the outline of the first 3D model based on the datum axis to be a locate point at the computing device; f) extending from the locate point along another two of three axes to search all of the coordinate points within the outline at a substantially similar height of the datum axis with the locate point at the computing device; g) reserving the coordinate information of the coordinate points being continual and capable of constituting a plane area at the computing device; h) after the step g), if the locate point is not a highest point of the outline on the datum axis, amending a value on the datum axis of the locate point by adding a fixed variable at the computing device, wherein the fixed variable is a value of a desired precision of the 3D object; and i) after the step h), executing the steps f), g), and h) according to the amended locate point at the computing device w) printing the 3D object.