Dahegu rice resources in Jiangxi Province are rich and are favorable for their special quality. No genetic study and quality improvement of Dahegu rice have been reported, and the plant stature is in need of improvement. In this study, SNP (single nucleotide polymorphism) markers were used to analyze the genetic characteristics of Dahegu rice varieties from Yiyang, and RVA (Rapid Visco Analyser) was used for quality determination. The results showed that 40 pairs of SNP primers detected 82 alleles in 20 materials, among which Dahegu rice varieties had indica frequency between 0.025 and 0.100, and were determined to be of japonica rice type. The viscosity of Dahegu rice grain was an accumulation process through grain maturation, whereas the amylose content was fixed before grain maturation. RVA parameters were closely related to physicochemical properties, and especially the rice grain length was negatively correlated with breakdown value. Pure milled rice grain rate and amylose content were the major gene traits. Compared with soft cultivated rice, the peak time was a key parameter to judge Dahegu rice. Through the screening analysis of the SNP and the viscosity, excellent japonica parents with similar quality and complementary traits were selected, such as brown-chaffed Nongju Ⅲ with the softest grain texture, brown-chaffed Mianhuada with the most stable quality, long-grained Nongkesuo Baikeda as a favorable breeding resource, and Wanyunjing 11036 as a choice breeding material for improving plant stature of Dahegu rice. These results would provide a guidance for the genetic improvement of Dahegu rice.