Objective The rice blast resistance gene Pi2 has broad spectrum resistance to physiological race of rice blast. Developing and evaluating KASP molecular markers for Pi2 will provide a convenient and reliable gene typing method for molecular breeding of rice varieties with blast resistance. Method Two materials H-74 and H-78 with different resistance and genetic relationships selected from 593 natural populations were used to develop KASP marker for the SNP sites in the core region of the Pi2 gene, named Pi2-C3. Result Using the marker Pi2-C3, 84 materials from the natural population were genotyped, and the results showed that the Pi2-C3 marker accurately distinguished the Pi2 loci of different rice materials into resistant, heterozygous, and susceptible genotypes, which was an efficient method for identifying the blast-resistant gene Pi2. The marker Pi2-C3 was used to detect the materials in Yangjiang disease nursery. Combined with the phenotypic investigation, it was found that 46 materials containing Pi2 gene showed different degrees of rice blast resistance, which indicated that the marker could be used to detect the incidence of materials in disease nursery. Conclusion This study develops a specific molecular marker Pi2-C3 for accurately detecting the Pi2 gene using the KASP technology, and establishes a KASP genotyping system for rice Pi2 gene. It has important application value for improving the efficiency of resistance breeding and improving blast-resistant rice varieties.