The invention discloses a device and method for measuring a three-dimensional temperature field of laser-induced plasma. According to the device, a plurality of groups of cameras are arranged around the laser-induced plasma in a distributed mode, and each group of cameras includes two cameras with optical filters with different central wavelengths installed at front ends of lenses. All the cameras are triggered strictly synchronously through a synchronous external triggering device, and projection images of different angles and different characteristic spectral lines of the laser-induced plasma at the same time are obtained. The spatial brightness distribution of the two characteristic spectral lines of the laser-induced plasma is calculated based on the obtained projection images of the laser-induced plasma according to the algorithm for reconstructing the three-dimensional image of an objected by means of projection, and finally the three-dimensional temperature field of the laser-induced plasma is calculated according to the relative spectral line intensity method. The device and method have the advantages that the device is simple, the method is easy to implement, measurement precision is high, and the range of measurement objects is wide, and the device and method can be used for online detection of physical parameters of laser-induced plasma during laser processing, quality monitoring during laser processing and other aspects.