The LHCf experimnt is a zero-degree measurement at LHC dedicated to verify hadron interaction models used for air shower development of ultra high energy cosmic rays(UHECR) at 10**17eV. The experiment installed a pair of small EM calorimeters in the beamline 140m apart from IP1 where ATLAS experiment exists, Energy spectrum of pi0's, gamma's and neutrons produced at 0 degree which quite relevant for air shower development of cosmic rays will be measured for the first time at such high energy. The result will be important to understand current enigma of energy and composition of UHECR's measured by AGASA, HiRes and AUGER. The status of experiment will be reported.