Abstract: The testing method of multi-bit upset in SRAM FPGA by pulsed laser was investigated. There are three types of multi-bit upsets according to physical location in FPGA, such as one byte in one frame, adjacent bytes in one frame and adjacent frames. Virtex-Ⅱ FPGA were irradiated by pulsed laser and heavy ions, and the species and relative positions for multi-bit upset were obtained. The relative physical positions of multi-bit upset induced by pulsed laser and heavy ions are same. The saturation cross-sections of multi-bit upset induced by pulsed laser and heavy ions are consistent. The pulsed laser testing is fit for the investigation of multi-bit upset in FPGA.