The radial tyre tread rubber was powdered by ultra-high pressure water jet for recycling, and NMR, FT-IR, SEM and grain size analysis were performed to study the physical and chemical structure of the rubber partial. It is found that the tread rubber is desulfurized at room temperature during the powder process. With increase of the pressure, the desulfurization degree rises firstly to achieve the optimal degree at 200 MPa, the NMR signal of internal chains reduces to 54.85%, after that the desulfurization degree reduces. The desulfurization mechanism was discussed and the shear stress field caused by ultra-high pressure water jet is considered to be the major reason of the desulfurization.