Accurate 3-D understory information obtained by terrestrial laser scanning usually requires the registration of multi-station scanning point cloud data. In order to reduce the need for additional equipment or functions when collecting forest laser scanning data, a forest laser scanning data registration method using smartphone positioning and orientation data was proposed. Firstly, initial transformation parameters were calculated based on the positioning and orientation from the smartphone. Then search space was generated from the initial transformation parameters, and different parameters were further evaluated by the proposed two-level objective functions using stem positions to obtain final registration result. During the evaluation process, stem positions were filtered by the distance between two scanner positions. The results of the registration test conducted on six pairs of measuring stations showe that the average rotation angle error 4.3′, horizontal and vertical translation errors obtained are 8.3 mm and 35 mm, respectively. The proposed method can improve the registration accuracy and efficiency and has high stability, and smartphone can provide effective auxiliary information for registration with canopy height (less than 11.5 m).