The invention discloses a multiple PCR (Polymerase Chain Reaction) detection kit, a special primer and a multiple PCR detection method for two kinds of seed-borne diseases on rice. The two kinds of seed-borne diseases are xanthomonas oryzae pv.oryzae and xanthomonas oryzae pv.oryzicola. A pair of special primers X-b for detecting the xanthomonas oryzae pv.oryzae and a pair of special primers X-t for detecting the xanthomonas oryzae pv.oryzicola are designed for the kit and the method, wherein the fragment length of a target product of each primer X-b is 461 bp; the fragment length a target product of each primer X-t is 348 bp; when the causes of the two kinds of diseases are detected at the same time, a multiple PCR reaction system as well as reaction conditions are optimized. According to the multiple PCR detection kit, the special primer and the multiple PCR detection method disclosed by the invention, the detection procedures of the causes of the two kinds of diseases are detected at the same time, the operation is simple and convenient, and quick and accurate, the cost is lower, and cloning, sequencing and sequence alignment are not required.