The loan loss reserve of the commercial bank could qualify and measure the credit risk that bank assume. However, the loan loss reserve may become the tool for the bank manager to manipulate the earnings. The executive of the bank may via the loan loss reserve of the discretionary accruals to give rise to the “earnings management” to undertake congruence of the analysts‘ standpoints of the earnings forecasting. This study analyze the commercial bank with the different attributes, include the old bank and new bank, share price higher than the net worth and lower than net worth, the accounting income can meet the earnings forecasting and can't meet. When the bank whose the accounting income can meet the earnings forecasts, may exist the action of the “earnings management”; reasoning if the operation condition of the bank good, can appropriate more of loan loss reserve, else if future operation not good, then may appropriate less loan loss reserve to conform the expectancies of security market investors.