Large High Altitude Air Shower Observatory (LHAASO) is a composite cosmic ray observatory
consisting of three types of detectors: KM2A, WCDA and WFCTA. One of the main scientific
objectives of LHAASO is to measure the cosmic ray spectrum and composition precisely. With
hybrid detection of WCDA and WFCTA, one can further study the "Knee" of cosmic rays from
100TeV to 10PeV. The original components of cosmic rays can be effectively distinguished with
four parameters provided by WFCTA, WCDA and MDA, respectively. The energy reconstruction
resolution of proton shower is about 20% reconstructed only by WFCTA. Combining with the
energy flow of shower core provided by WCDA, a better energy resolution is expected.