The luminescence mechanism of the nano ZnO is introduced.The UV emission commonly exists at about 380 nm in the room temperature photoluminescence(PL) spectrum of the nano ZnO and rare UV emission at 357 and 377 nm is reported,and the luminescence mechanism of which is listed.The continuous luminescence band for the deep level spectroscopy is observed at 400-550 nm ordinarily,and the phonon sideband and replication spectrum are also observed at the deep level spectroscopy.The free exciton emission(FX),neutr...