In order to promote the application of phytosterol ester, a new kind of catalyst was developed on the basis of traditional enzymatic synthesis method. Pickering emulsion catalyst (CRL@PE) with two-phase structure was constructed using isoctane and Candida rugosa lipase and employing nanotube as emulsifier. Then the CRL@PE was used to catalyze the synthesis of β-sitosterol linolenic acid ester with β-sitosterol and α-linolenic acid as substrates. The effects of temperature, enzyme dosage, linolenic acid concentration and reaction time on the conversion rate of phytosterols were studied by single factor experiment and central composite design of response surface methodology. The optimal process parameters were obtained as follows: temperature of 29.45 oC, lipase dossage of 10.97 U, linolenic acid concentration of 42.35 mmol/L, reaction time of 350.7 min, and phytosterol conversion rate was 96.8±0.7% at these conditions. After reuse of CRL@PE for 10 times, the phytosterol conversion rate was 96.86%, showing that the catalyst had good stability.