This study aims to analyze patent portfolio of three-dimensional printing industry, future trends, as well as to explore how patent strategy could be developed. A total of 1089 patents that belong to 3D printing technologies are retrieved from the United State Patent and Trademark Office (USPTO) patent database for analysis. There are two objects in this research: first, from the patent perspective to distinguish how emerging three-dimensional printing is. The other object is using knowledge flow tool to demonstrate how diversified the 3D printing industry can be. Moreover, by analyzing the 1089 of 3D printing patents, some important implication, i.e. technology life cycle, patent citations, patented characteristics information and knowledge flow, can be uncovered to understand the overall 3D printing technology trends, in terms of (1) Country (2) Industry (3) Organization levels.