By analyzing data samples taken at the center-of-mass energies √ s = 3.773 GeV and √ s = 4.009 GeV with the Beijing Spectrometer (BESIII) detector at the Beijing Electron Positron Collider (BEPCII), we determined the D + (s) decay constants, the form factors of semileptonic decays of D meson, the CKM matrix elements |V cs(d) |, the D + (s) hadronic decays, and we search for charm rare decays. In this article we briefly report the results.