It is essential to research some key technical measures for japonica rice varieties as transplant density, suitable amount of fertilizer to exploit the advantages of growth, yield potential and yield, and their cold resistant to ensure the development of japonica rice varieties in Yen Bai province. This research was conducted with J01 rice variety in Van Chan and Tram Tau districts, Yen Bai province for two years from 2011 to 2012. With the transplant density of 45, 50, 55 plant clumps/m2 and fertilizer application of 1200 kg of Song Gianh micro - organic fertilizer + 100 kg N + 90 kg of P2O5 + 80 or 100 or 120 kg K2O fluctuations, the obtained result was: With the transplant density of 50 plant clumps/m2 and fertilizer base of 1200 kg of Song Gianh micro - organic fertilizer + 100 kg N + 110 kg P2O5 + 100 Kg K2O, the highest yield in spring season was 67,1 quintal / ha and 60,4 quintal/ ha in summer season.