Based on Feltham-Ohlson Model,this paper has set up a model that enterprise net assets change with time and brings the accrual of impairment provision into it.Through an analysis of the model,the authors find the follows: In general,the realization of maximum of enterprise value has nothing to do with voluntary accounting changes based on impairment provision.Whether there are voluntary accounting changes or not,the refinancing constraints will reduce the IOS,i.e.enterprise value.On the condition of refinancing constraints,that the enterprise adopts voluntary accounting changes of reducing the accrual of impairment provision in order to meet the demand of refinancing will cause the further decline of IOS,i.e.enterprise value.