Aim To research the intramyocardial microcirculatory derangement and its mechanism during myocardial stunning. Methods Twelve dogs underwent 15 or 60 min left anterior descending coronary artery (LAD)occlusion, followed by 120 min reperfusion. Another six dogs underwent sham operation. Myocardial contrast echocardiography (MCE) was performed intravenously using C3F8 exposed sonicated dextrose albumin and blood samples were taken from coronary venous sinus at different time points. Electrocardiogram gated end systolic images in short axis were acquired in harmonic mode and digitized on line. Background subtracted peak videointensity(PVI), ascending slop(α) and early descending slop(β) of MCE curve in stunned and normal myocardium areas were measured from MCE. The ratios of PVI, α, and β between stunned and normal myocardium areas were calculated. Results A marked increase in PVI occurred in all dogs with stunned myocardium in the early period of reperfusion and the PVI restored to the pre occlusion level after 60 min of reperfusion. The ratios of PVI, α, and β in the early period of reperfusion were significantly higher than the pre occlusion levels, and gradually restored toward their pre occlusion levels. Plasma lactic acid concentrations significantly increased in the early period of reperfusion, and restored to the pre occlusion levels by 120 min after reperfusion in the 15 min LAD occlusion group, but not in the 60 min group. No changes in PVI, three rations, and plasma lactic acid levels during the experiment were observed in the sham operated group. Conclusions The microcirculation of stunned myocardium is hyperdynamic. The anaerobic metabolism of stunned myocardium enhances. The intramyocardial microcirculation "short" is a possible mechanism of the microcirculatory dysfunction of stunned myocardium.