The graphics processing unit (GPU) has become a popular device for seismic imaging and inversion due to its superior speed-up performance. We implemented GPU-based full-waveform inversion using the wavefield reconstruction strategy. Because computation on the GPU was much faster than CPU-GPU data communication, in our implementation, the boundaries of the forward modeling were saved on the device to avert the issue of data transfer between the host and device. We adopted the Clayton-Enquist absorbing boundary to maintain the efficiency of the GPU computation. A hybrid nonlinear conjugate gradient algorithm combined with the parallel reduction scheme was used to do computation in GPU blocks. The numerical results confirmed the validity of our implementation.