Reconfigurable Intelligent Surface (RIS) to aid wireless communication has received much concern in academia and industry. However, the element in the existing RIS design method cannot be controlled individually, thereby the accuracy and efficiency of beamforming are insufficient. In this paper, a method of realizing RIS with high accuracy by FPGA is proposed. On the basis of making use of FPGA to control the positive intrinsic-negative (PIN) diodes, 2-bit elements on the RIS are available and can be controlled individually in an unsophisticated way. The experimental results indicate that our proposed method can significantly improve the accuracy and efficiency of beamforming.