We can degrade xylan into xylose in high efficiency with the synergistic action of β-xylosidase Ruxyn. We try to detect the activity of enzymes with 3,5-Dinitrosalicylic acid, but it is not so obvious. We speculate this might result from the facts that there is a big difference of the expression of foreign protein among different carriers of Pichia pastoris or different yeast strain, and that inappropriate ferment condition can result in low or even no activity of enzymes. In future research, we will try to enhance activity of enzymes by picking up suitable carriers and yeast strains and figuring out the optimal reaction conditions. We construct the gene on the carrier displaying on the surface of Pichia pastoris and express it it in Pichia pastoris with electroporation. Then we detect the expression on the surface of Pichia pastoris by observing with fluorescent microscope and by flow cytometry analysis.