Abstract: In order to improve quality of Mantou and reduce its staling rate during storage, TA-XT plus and nuclear magnetic resonance (NMR) techniques were used to measure the firming and water distribution of samples of Mantou, which were added xylanase. Then, effects of xylanase on the staling rate of samples were studied. The results showed that the hardness of the crust and core of Mantou increased slowly during storage of 0~36h. The samples added XYL were less hard than the control sample. The hardness increased significantly when it was 36 h, especially the samples added L-XYL. Meanwhile, the proton signal A and A1 of Mantou samples decreased continuously during storage. The proton signal of samples added xylanase decreased slowly during storage of 0~36h, and the samples added solid state of xylanase (S-XYL) also decreased slowly during storage of 36~120h. While, the proton signal of the addition of L-XYL to samples decreased rapidly.Therefore, the staling rate of samples added xylanase was slower during storage of 0~36h, and the samples added S-XYL was slower during storage of 36~120h, however, the staling rate of samples added L-XYL was faster.