This paper presents a rate control scheme for low delay video communication of the High Efficiency Video Coding (HEVC) standard. To prevent the buffer overflow and underflow under small buffer size constraint in low delay communication, the state-of-the-art R-λ algorithm is improved for more accurate bit allocation. A new bit allocation method based on the buffer status is proposed to control the buffer better, which is very important in low delay applications. Experimental results show that compared with the original R-λ algorithm, the proposed scheme has a smaller bit fluctuation and can avoid buffer overflow and underflow with a smaller buffer size, which often means a lower delay, and the PSNR degradation is negligible.