Many bridges have been constructed using precast components because they offer faster production, lower cost, and more efficient construction compared to conventional in-situ construction. For coupled behavior of bridges slabs and girders, shear pockets on the deck slab and shear connectors on the girder need to be properly connected. However, precast girders can be easily deformed once they are placed in-situ because of their heavy weights, time dependent effects of creep and shrinkage, pre or post tensioning, etc. Once the girders are deformed, shear pockets and shear connectors may no longer match properly. This study proposes a technique which can automatically identify mismatches between shear connectors and shear pockets using LiDAR and identify the optimal placement of precast deck slabs with respect to precast bridge connectors. First, precast girders are scanned using a LiDAR. Then, unnecessary noise data is removed and the coordinated of the point cloud data is transformed with respect to shape of the precast girders. Afterwards, the locations of shear connectors on the girder are estimated from the point cloud data. Finally, deck slabs are optimally placed to minimize the mismatch using Levenberg-Marquardt (LM) method. To validate the effectiveness of the proposed technique, an experiment was conducted on a small-scale test specimen and on a real precast girder. The experimental results demonstrated that the proposed technique can properly and efficiently estimate the optimal placement of precast deck slabs with respect to precast girders.