Passive Q switched operation of a laser diodepumped laser is studied with a saturable absorber GaAs as a passive Q switched component and F-P output coupler. The Q switched pulse duration is 47ns, pulse repetition rate is 1183 kHz, pulse average power is 430mW, beam quality M 2 is equal to 1 13 and the laser threshold of passive Q switching is 1700mW. We performed numerical calculations of coupled wave equations for the case of GaAs playing the role as mentioned above, discussed the passive Q switched mechanism and the dependence of pulse duration, pulse repetition rate and average power on the pumping rate and laser cavity length, which was in good agreement with the experimental results. A brief and effective technique is provided for compact Q switched solidstate laser having multiple functions.