Abstract: The aims were to confirm the best amount of nitrogen application and the best additional manuring time of rice in black earth area of the Northeast. The field test was conducted with“day”as the unit, and the SPAD-502 was used to detect the dynamic change of the SPAD values of rice leaves under different treatments (N1-N6; PAD40, SPAD38, SPAD36, SPAD34 and SPAD32) for 45 consecutive days. The results showed that SPAD values increased significantly during the 7 days after the application of nitrogen additionally. As the amount of nitrogen application increased, the SPAD values of rice leaves increased significantly and the peak value was relatively high, meanwhile it reached the peak earlier. When the amount of nitrogen application was 170 kg N/hm2, the crop output was 7078 kg/hm2, and with the additional manuring carried out at SPAD value of 40, the crop output was up to 9078 kg/hm2, which was the highest. Therefore, the best amount of nitrogen application for rice in black earth area of the Northeast was 170 kg N/hm2, SPAD value of 40 could be used to determine the best time of additional manuring from tillering stage to booting stage.