The AlGaInAs semiconductor saturable absorber grown by Metal-organic Chemical Vapor Deposition is used as the saturable absorber in a 808 nm LD-pumped passively Q-switched Nd∶YVO4 laser at 1.06 μm.The dependences of the pulse energy,pulse width,pulse repetition rate on the pumping power are measured.With an incident pump power of 10.57 W,an average output power of 3.4 W is obtained,and the corresponding slope efficiency is 39%.At this pump power,the repetition rate reaches the maximum value of 101 kHz.The Q-switched pulse width reaches the minimum of 1.76 ns with an incident pump power of 8.07 W.Using the rate equations of passively Q-switched lasers,the theoretical results for the pulse energy,pulse width,pulse repetition rate are obtained,which show an agreement with the experimental results on the whole.