The encoding process of vector quantization (VQ) is computational expensive. To reduce the distance computations between vectors， many methods use inequality relations to make distance estimations with less computational cost. This paper aims at extending the method using two-bounds triangle inequality proposed by Chang C C et al by improving reference the vector selection. The experimental results show that our proposed method can increase the ratio of codeword rejection by 3.735%9.976%， and reduce the encoding time by 6.03%35.25%.