LHAASO will be an EAS array located in the Sichuan Province (China) at an altitude of 4410 m a.s.l. The array, covering an area of 1 km^2, will be composed by three main detectors: a central water pool to detect low energy events, an array of scintillator detectors to measure the electromagnetic EAS component and an array of shielded water tanks to sample the muon component. I will describe the expected performances of the experiment and its potential both in the search for gamma ray sources from 100 GeV to 100 TeV and in the study of charged cosmic primaries from 100 TeV to 100 PeV.