The DArk Matter Particle Explorer (DAMPE) satellite is a powerful space detector launched on December 17 2015. The main objectives of the mission are in the research for Dark Matter signatures thanks to the detection of electrons and photons in an energy range going from few GeV up to 10 TeV. Moreover, insights on the origin and propagation mechanisms of cosmic rays are also expected thanks to nuclei flux measurements up to 100 TeV. In this context the charge (Z) measurement is crucial to distinguish the different chemical components of cosmic rays and to check the models of propagation in the galaxy. The DAMPE detector is composed of the following sub-detectors: a Plastic Strip scintillator Dectector (PSD), a Silicon-Tungsten tracKer (STK), a Bismuth Germanium Oxide (BGO) imaging calorimeter, and a NeUtron Detector (NUD). The Z-measurement is performed by the PSD and the STK. In this document after a detailed description of the STK, the first results on the absolute ion charge identification using more than one year of STK on-orbit data are discussed, together with the applied calibration procedure.