Abstract: The effects of different nitrogen rates on culm traits and lodging resistance were studied for a two-line super high-yielding hybrid rice combination Guangliangyou 676. The results indicated that the length of internodes, especially the fourth and fifth internode from the top, increased with the increase of nitrogen application rates, and had an extremely significant positive correlation with nitrogen application rates, showing that nitrogen application could increase internode length of rice. The diameter of each internode increased with the increase of nitrogen application levels. Nitrogen application had no effect on culm wall thickness. The height and weight of each internode to the top of the spike all had a very closely significant correlation with nitrogen application levels. The breaking-resistant strength of each internode decreased with the increase of nitrogen application rates, but had no significant difference. The bending moment and lodging index both significantly increased with the increase of nitrogen fertilizer rates, and both had very closely significant relation to nitrogen application rates. Guangliangyou676 has better resistant lodging ability below 20 g·m^-2 of nitrogen application rate, but is subjected to lodging easily under excessive nitrogen fertilizers.