This article develops the hardware and software of an automatic measurement system for laser plasma shock wave,which is based on the principle of beam deflection.The system applies respectively computer and programmable logic controller (PLC) as up computer and down computer and takes the way of communication between up computer and down computer to control stepper motor and two dimensional movable rack to alter the location of detecting laser and uses single mode fiber to transmit beam deflection signals to digital osciloscope.Finally,the computer analyses and processes the signals.Using the system we measured the attenuation processe of laser plasma shock wave and got better experimental results.