By using GaAs saturable absorber, the running of a diode-pumped Q-switched intra-cavity frequency-doubled Nd∶YVO4/KTP laser is realized. The dependences of pulse width, pulse repetition rate, pulse energy and peak power on pump power are measured with different thickness of GaAs. At 3.22 W of pump power, the laser Q-switched by 300 μm GaAs produces 53.2 ns pulses at a pulse repetition rate of 381 kHz. The pulse energy is 0.18 μJ. The rate equations of intra-cavity frequency-doubling laser Q-switched by GaAs are introduced to analyze the experimental results. The numerical calculations of the rate equations are consistent with the experimental results.