Nd∶YAG crystal is end-pumped by a 5W laser diode.Through reasonable design of membrane system,single line fundamental frequency light is respectively obtained by using birefringent filter(BF)and etalon.A 10 mm long type-Ⅰcritical phase matching LBO nonlinear crystal is adopted for intracavity frequency doubling,and then a stable single-line 561 nm laser output is obtained.The process that birefringent filter and etalon restrain other competition lines is analyzed theoretically,and it is found that the use of birefringent filter can obtain a narrower line width output and the use of etalon can obtain a higher output power.The theory analysis agrees with the experimental results.The output power is 227 mW and 254 mW at the pump power of 4.8 W respectively,with the slope efficiency of 6% and 6.68% respectively.