Abstract: Objectives: The objectives of the study were to determine (1) The level of mechanical resistance of oil palm seedlings to drought stress in some application doses of boron (B) and silicon (Si) and (2) The mechanism of B and Si actions to induce the mechanical resistance of oil palm seedlings to drought stress. Methodology: Field trial was arranged in the Randomized Complete Block Design (RCBD) factorial. The first factor was the dose of B, namely 0.00, 0.17, 0.44, 0.87 and 1.31 g per plant. The second factor was the dose of Si, namely 0.00, 1.15, 2.31, 3.46 and 4.69 g per plant. The data were analysed using analysis of variance (ANOVA) and the means were separated using Duncan’s Multiple Range Test (DMRT) at 5% level. Meanwhile, the optimum dose of B and Si were determined using regression analysis. Results: Results showed that the optimal dose of B which can induce mechanical resistance of oil palm seedlings to drought stress was ranges from 0.64-0.73 g per seedling. Indicators that can be used to detect a positive effect of B application were the increase of lignin and suberin scores in the root as well as plant height and stem diameter when they were applied using B in the range of 0.64-0.73 g per seedlings. Meanwhile, the indicator which was used to detect a positive impact of Si applications was the increase in root hardness. Scores of lignin and suberin in the root cannot be used as indicators of the resistance level, because they were not responsive to Si application. Conclusion: The optimal dose of Si to induce resistance of oil palm seedlings to drought stress could not be determined due to the regression relationship between the dose of Si application with the roots hardness has a linear trend, when the dose of Si application increase up to 4.65 g per seedlings.