Hejiang 20 is one of the most important backbone parents in cold region. In this paper, the rice blast resistance gene Pi-ta genetic between Hejiang20 and its 25 transmission in derivatives were analyzed by using the dominant rice Pi-ta gene markers. The results showed that frequency of resistance genes Pi-ta was 63% in the first generations of Hejiang20 derivatives，and the frequency of occurrence in the second-generation derivative varieties was 33%, and the frequency of occurrence in the third-generation of derivative varieties was 9%. Disease transfer of genes Pi-ta Hejiang 20 just liked as derivative map. The spectral analysis of anti-Pi-ta results indicated that it was a positive correlation forresistance gene between which in the offspring and which in the derived varieties. These results could be caused by the loss of resistance genes in the species, which was also may be one of the main reason to determine the levels ofrice for the different rice varieties.