Finite difference time domain (FDTD) schemes are widely applied to analyse sound propagation, but are computation-intensive and memory-intensive. Current sound field rendering systems with FDTD schemes are mainly based on software simulations on personal computers (PCs) or general-purpose graphic processing units (GPGPUs). In this research, an accelerator is designed and implemented using the field programmable gate array (FPGA) for sound field rendering. Unlike software simulations on PCs and GPGPUs, the FPGA-based sound field rendering system directly implements wave equations by reconfigurable hardware. Furthermore, a sliding window-based data buffering system is adopted to alleviate external memory bandwidth bottlenecks. Compared to the software simulation carried out on a PC with 128 GB DDR4 RAMs and an Intel i7-7820X processor running at 3.6 GHz, the proposed FPGA-based accelerator takes half of the rendering time and doubles the computation throughput even if the clock frequency of the FPGA system is about 267 MHz.