Abstract: OBJECTIVE To observe the effect of humidified oxygen therapy with Xiexiang formula on myocardial injury markers and pathological morphology of cardiopulmonary tissue of mice with myocardial infarction， and to evaluate its protective effect on ischemic myocardium and its safety on lung tissue. METHODS 40 C57BL/6 male mice were divided into the normal control group (control group)， the model control group (ISO group)， the Xiexiang formula paste group (XXF group) and the Xiexiang formula paste + volatile oil group (XXFHF group). Myocardial infarction models were established through ISO induced method. ISO group was given 50% oxygen inhalation， XXF group and XXFHF group were given Xiexiang formula paste and Xiexiang formula paste + volatile oil mixed with humidified oxygen inhalation， respectively， 8 h/d for 7 d continuously. RESULTS The increase of LDH， CK and CK-MB in XXF group and XXFHF group were lower than that of the ISO group (P<0.05). LVEDD and LVESD in the XXF group and XXFHF group decreased obviously (P<0.05)， but EF and FS levels significantly increased (P<0.05). Myocardial histopathology in XXF and XXFHF groups showed small range of myocardial necrosis， the extent of necrosis was significantly lighter than that in the ISO group， and inflammatory cell infiltration and interstitial edema were also lighter than those in the ISO group. No obvious pathological changes were found in lung tissues of all four groups. CONCLUSION Humidified oxygen therapy with Xiexiang formula can protect myocardium in ischemic state， have no pathological effect on the lung tissue. As an adjunctive therapy， it is safe and effective in the treatment of AMI.