The determination of energy spectrum of different species above 100 TeV is still one of the main challenges in cosmic ray physics. The energy spectrum of the individual component is an important tool to investigate the cosmic ray production and propagation mechanisms. A preliminary results of mixed proton and helium energy spectrum, obtained with the combined data of six Cherenkov telescopes, one 150m×150m water Cherenkov detector (WCDA-1) and half muon detector and scintillator detector array in LHAASO experiment will be reported. The preliminary results will be analyzed by using the combined data obtained between October 2020 and February 2021. By means of a multiparameter technique, the resolution of reconstructed energy, shower direction, shower core location and composition identification are improved.