The space experiment DArk Matter Particle Explorer (DAMPE) is developed and supported by an international collaboration including institutes and universities from China, Italy and Switzerland, DAMPE is designed to measure cosmic-rays (CRs) and gamma-rays in space, and since December 2015 it is collecting data with smooth and continuous operations. The instrument consists of two layers of plastic scintillators to identify the charge of individual elements from proton to iron, a silicon-tungsten tracker providing accurate particle tracking and complementary charge measurement, and a thick calorimeter (32 radiation lengths) providing a good potential to measure CRs in the energy range from 50 GeV up to 100 TeV. This measure is of fundamental importance to shed light on the mechanism of acceleration and propagation of cosmic rays in the Galaxy. In this report, the selection criteria of the carbon and oxygen components will be illustrated; Some comparison of charge between Monte Carlo data and flight data have been done. And efficiency of event selections also be validated by Monte Carlo simulations.