Three ionic liquid-based silicas were synthesized, and variable adsorption conditions were optimized by RSM. Under the optimized condition, 0.1mg/mL of β-sitosterol in methanol: water (60:40, vol%) with 10 min adsorption, Sil-HIm was selected and was applied as the sorbent in SPE. Two samples such as peanut and corn were used and after washing by water and acetone and eluting by methanol-1% vol acetic acid, 0.0008 mg/g and 0.006mg/g of β-sitosterol were detected from them with satisfactory recoveries. The proposed Sil-IL-SPE could be potentially applied to separation, purification and determination of β-sitosterol from complicated natural products.