Five homologous genes of digalactosyl-diacylglycerol synthase(OsDGD) were obtained through the approach of comparative genomics from rice. From the analysis of biochip expression, the result indicated that OsDGD genes were involved in thermal and drought stress. By using real-time quantitative PCR analysis and adopting flag leaves of the young panicle at 6–7 stages of cultivar Oryza sativa Nipponbare 9311 and N22 as materials, the expression levels of 5 OsDGD genes in response to thermal stress showed that OsDGD1, OsDGD2 and OsDGD3 were obviously induced by thermal stress in N22 line, which had higher basal thermo-tolerance level. By taken all test results into consideration, we inferred that OsDGD genes were involved in thermal stress of signal transduction pathway in rice.