Large High Altitude Air Shower Observatory is a composite cosmic ray and gamma ray observatory consisting of three sub-detector arrays: the kilometer square array (KM2A), the water Cherenkov detector array (WCDA) and the wide field of view Cherenkov telescope array (WFCTA). LHAASO is under construction now and the 1/4 LHAASO array is planned to be completed in this year.
In this work, samples of the light components are selected by the simulation of hybrid observation with 1/4 LHAASO array. Boosted Decision Trees (BDTG) in Toolkit for Multivariate Analysis (TMVA) is used for the selection of primary particles in cosmic rays. The apertures of pure proton and mixed proton and helium samples are 900 m^2Sr and 1800 m^2Sr respectively with high purity. Moreover, a prospect of proton and mixed H&He spectra with energies from 100TeV to 4PeV is also presented.