The finding of gaseous signaling molecule NO, CO and H2S, and the advocacy of "gas biology" concept have provided a novel thinking for the study of Huoxue Huayu (HXHY, a traditional Chinese medicine method of promoting blood circulation to remove blood stasis). The concept "Qi" in TCM and gaseous signaling molecule are correlated in respects of their source and mesomeric function. Study of HXHY could only be deepened through an overall cognition on blood stasis syndrome with the view of Qi-blood correlation.