Abstract: Longjing12 was bred by rice research institute of Heilongjiang academy of agricultural sciences. It was a new rice variety that was large grain, early maturity, good quality , high yield and good resistance to diseases. Longjing12 was approved by the Heilongjiang Crop Variety Examination Committee in 2003, and the cultivated area reached 0.07 million hectare in 2004. The result showed that longjing12 was a good rice variety and a large grain germplasm with high quality.