3D reconstruction has been an active research topic with the popularity of consumer-grade range cameras, and the whole process mainly consists of registration and integration. Most recent methods pay their attention to making depth maps aligned with each other, but the step of integration is simply conducted by weighted average for the volumes of truncated signed distance function (TSDF), thus the relationship between individual and integrated TSDF representations is not well explored. In this paper, under the framework of voxel-level optimization, a novel method is proposed for TSDF volume integration. Considering camera distortions, each individual TSDF volume is corrected by a non-rigid transformation. Based on the consistency of TSDF values of individual and integrated volumes, both the final global TSDF representation and the transformation parameters are calculated by solving the optimization problem. Experimental results demonstrate that more satisfactory reconstruction performance can be obtained by our proposal.