  Large High Altitude Air Shower Observatory(LHAASO) is a composite cosmic ray
observatory consisting of three detector arrays: kilometer square array (KM2A)
which includes the electromagnetic detector array and muon detector array,
water Cherenkov detector array (WCDA) and wide field of view Cherenkov
telescope array (WFCTA). One of the main scientific objectives of LHAASO is to
precisely measure the cosmic rays energy spectrum of individual components from
1014 eV to 1018 eV. The hybrid observation will be employed by LHAASO
experiment, in which the lateral and longitudinal distributions of the
extensive air shower can be observed simultaneously. Thus many kinds of
parameters can be used for primary nuclei identification. In this paper, high
purity cosmic ray simulation samples of light nuclei component are obtained
through Multi-Variable Analysis. The apertures of 1/4 LHAASO array for pure
proton and mixed proton and helium (H&He) samples are 900 m2Sr and 1800 m2Sr
respectively. A prospect of proton and H&He spectra from 100 TeV to 4 PeV is
discussed.
