Many detectors on the ground, on balloons and in space already made a lot of efforts to improve cosmic-ray measurements, and several others are currently continuing them. The DAMPE detector is designed to pursue this task. The DAMPE Silicon Tungsten tracKer (STK) was assembled after testing individually all its components. The signals of the read-out chips of the silicon ladders were calibrated with an analysis based on ground and orbit data. A charge-loss correction of the tracker response was performed on-ground and on-orbit. We performed an analysis on 30 months of data from DAMPE, dedicated to calculate precisely the proton flux. The proton flux measured with this analysis allowed to improve the current knowledge of the energy dependence of the proton spectrum, which is the key element in understanding the origin, propagation and acceleration of cosmic rays in the Universe.