A total of 126 Phytophthora infestans isolates were collected from Harbin，Suihua and Qiqihar
Cities of Heilongjiang Province from 2015 to 2017. Analysis on their mating types，mtDNA haplotypes，SSR
genotypes and multi-locus genotypes were carried out. The results indicated that 3 mating types of A1，A2 and self-fertility were found in 126 strains isolated，accounting for 88.1%，6.3% and 5.6% of the total isolates，
respectively. Two mtDNA haplotypes，Ⅰa and Ⅱ a，were identified，accounting for 17.5% and 82.5% of the total
number of isolates，respectively. Seven SSR genotypes，F-01，F-02，F-03，F-05，F-06，D-03 and G-02，
were identified from 126 isolates tested. Among them，the F-01 genotype（77.8%）was dominant genotype.
A total of 9 multi-locus genotypes were identified by systematic analysis of P. infestans，and the multi-locus
genotype A（65.1%）was the dominant genotype found in Heilongjiang Province. These results indicated that from
2015 to 2017，the population structure of P. infestans in Heilongjiang Province was very complicated year by year.
And the population structure of P. infestans in the Suihua City was the most complex.