The wastewater from industrial smelting process contains heavy metals such as arsenic (As) that produce serious environmental pollution and cause actual harm to the health of people. It is necessary to control the pollution at the source and achieve a real-time and online monitoring. The laser-induced breakdown spectroscopy (LIBS) is a new elemental analysis technique, and has the advantage of rapid detection. An LIBS setup has been established. The Nd∶YAG laser beam is focused onto the sample, then the plasmas are produced. The emission spectra of plasmas are dispersed by an Echelle spectrograph and detected by an intensified charge-coupled device (ICCD). Experiments have been carried out on the industrial wastewater collected from the scene. The spectral lines of As element were obtained. The calibration curve of the line intensities versus the concentrations of the As element was acquired by the experiment. The calibration curve can be used for the quantitative analysis of arsenic element with an unknown concentration in the industrial wastewater. The results showed that the LIBS technique can be applied in the rapid detection of As element in industrial wastewater, and has wide range of applications.