Abstract: OBJECTIVE To investigate the effect on hypoxia in mice and myocardial cells in vitro changes of Hongyexintong soft capsule. METHODS The hypoxic cardiac arrest time, myocyte primary culture A570 and the LDH activity of mice which were treated by Hongyexintong soft capsule at different doses were observed and compared with that treated by Xiangdan injection. RESULTS The high and middle dose group of Hongyexintong soft capsule could significantly prolong the time mice tracheal ligation of the heartbeat and increase cardiac hypoxia tolerance in mice. The high dose group of Hongyexintong soft capsule could obviously improve the NaCN-induced myocardial cell injury induced by primary A570 due to the decline, reducing the vitality of culture supernatant LDH. CONCLUSION Hongyexintong soft capsule has effect of improving the role of hypoxia in mice and protecting myocardial cell, which injuried by NaCN-induced.