Because any type of image sensor has the inevitable question of nonuniformity which directly affect the quality of image and its using range, the paper discusses the principle and algorithm of multi-point nonuniformity correction and designs the scheme of nonuniformity correction based on Complex Programmable Logic Device (CPLD). The CL512J Self Scanned Photodiode Array(SSPA) image sensor is used in the nonuniformity realtime correction experiment. The result of experiment shows the correction system can reduce the nonuniformity of this image sensor from 40% to 2%.