Objective To investigate the way and process of degradation behavior of acellular porcine aortic valve in vitro. Methods Acellular porcine aortic valve（n=90）were randomly divided into 3 groups （collagenase group, elastase group, control group）, 30 piece in each group . Behavior of acellular porcine aortic valve was degradated with 0.05mg/ml collagenase Ⅰ, 0. 05mg/ml elastase, phosphate buffered solution in collagenase group, elastase group and control group. The histomorphology, weight loss, value of protein and hydroxyproline were observed at 3,6,9, 12, 15 and 30d after degradation. Results The behavior of acellular porcine aortic valve of collagenase group and elastase group became poorer, looser and broken gradually in degradation. The weight loss of valve, the value of protein and hydroxyproline in vehiculum became greater gradually in collagenase group and elastase group（P〈0. 01）. Furthermore the effect of collagenase Ⅰ was b than elastase in degradation. Conclusion The effect of collagenase Ⅰ and elastase can degradate the acellular porcine aortic valve in vitro. Collagenase Ⅰ is b than elastase in degradation.