In order to study the germination and the ability of preharvest sprouting resistance of different mature degrees of Japonica giant embryo rice seeds, the seed and panicle germination experiment of different days after flowering of Japonica Xi-giant embryo-1 was conducted, the local variety of japonica rice Hexi-22-2 as control. The results indicated that the seeds can not germinate when the days of grain filling was less than 21 days, and the germination ability of mature seeds was 53.7%, the germination time of Japonica Xi-giant embryo -1 was 48h later than that of Hexi-22-2, and the process of germination had no obvious peak. The ability of preharvest sprouting resistance of Japonica Xi- giant embryo -1 was stronger than Hexi-22-2.