Rice is a silicon (Si)-accumulating plant species. It is estimated that a rice crop producing 1,000 kg yield will remove 130 kg Si from the soil, twice as much as the combined absorption of nitrogen, phosphorus, and potassium. The rice leaf folder (LF), Cnaphalocrocis medinalis (Guenée), is one of the most destructive rice pests in Asian rice-producing countries. Recently, major outbreaks of LF have been reported in many Asian countries including China, severely threatening rice production. Rice varieties resistant to LF have either a high Si cell density or high Si content in the leaf blade. Currently, LF populations are principally managed with chemical insecticides that have caused high residual, insecticide resistance and a resurgence of pests. Alternatively, cultivar resistance and crop management including Si amendment are being developed. There is increasing evidence showing a positive association between high plant Si content and resistance to insect herbivory in monocots and dicots. Si amendment can influence insect herbivores in several ways, including acting as a physical barrier, deterring feeding behavior, reducing food consumption efficiency and performance, and effecting herbivores at a transcriptional level through differential regulation of plant genes. In the present paper, we report the effects of Si addition to rice plants on feeding and oviposition preference and damage by the LF. We used the susceptible rice cultivar Taichung Native 1 (TN1) and added Si at 0.32 (high rate), 0.16 (low rate), and 0 g Si/kg soil (control). In preference tests, LF larval settlement and egg deposition on rice plants amended with Si at both the low and high rates were significantly reduced. Si amendment at the high rate significantly increased the Si and soluble sugar contents and C/N ratio and decreased the nitrogen content in rice leaves compared with the control; Si addition at the low rate significantly increased the C/N ratio and decreased the nitrogen content in rice leaves in comparison with the control. The damage rates decreased significantly in rice plants amended with Si at the high rate than that of the control. Our results indicate that Si addition to susceptible rice plants could enhance plant resistance to LF through reduced feeding and oviposition preference.