In this paper, one displacement monitoring technique using a smartphone based on the laser projection sensing method is proposed and developed. By means of a common laser device and a projection plate, structural displacement can be monitored using a smartphone. First, a laser spot centroid recognition method was utilized for displacement recognition. Next, one displacement monitoring APP (D-Viewer) based on the android platform was developed. To verify the feasibility of the proposed method, static and dynamic comparison experiments using two android smartphones were conducted. Finally, the mid span displacement of one suspension bridge model was tested using the proposed technique. The results show that this technique is a convenient, fast, low-cost structural displacement monitoring method with reasonable precision. (C) 2016 Elsevier B.V. All rights reserved.