To screen resistant rice varieties in Liaohe Valley to the rice stem borer Chilo suppressalis Walker, development of and damage by the borer larvae on the varieties were examined using intact-plant resistance evaluation method, and morphological and biochemical characteristics and number of silica cells of the rice varieties were determined to explore the potential resistance mechanisms. Percent of damaged plant was the smallest on the variety Yanfeng 47, and larval weight on Shennong 265 was the lowest. Percent of damaged plant was found to be strongly correlated with angle of the reciprocal 2nd leaf and Si content in stem, where the former is a positive logarithmic correlation and the latter is a negative linear one. And, a strong positive linear correlation was revealed between larval weight and stem diameter. Implications of the current results were discussed in the context of utilization of and future rice breeding for insect resistance.