The DAMPE (Dark Matter Particle Explorer) is a powerful space-borne experiment for direct detection of high-energy cosmic rays, electrons and gamma rays. While it was designed mainly to search for dark matter signatures in the electron and photon spectra, DAMPE distinguishes itself also by its capability to study the cosmic-ray fluxes of the primary species with unprecedented resolution (better than 40% at 800 GeV) in an energy range from few tens of GeV up to 100 TeV. The selection of the incoming particle is done by means of the Plastic Scintillator Detector (PSD), whose signal is proportional to the square of its electric charge. Selecting the H + He samples has the advantage of almost no background and very high purity. Here we present the preliminary results of the measurement of the proton + helium energy spectrum measured from 50 GeV to 30 TeV. The observed spectral features are also discussed and the results are compared with other measurements.