First lasing of the CAEP THz FEL(CTFEL)facility was obtained in August 29,2017.The facility consists of a GaAs photocathode high-voltage DC gun,a superconducting RF linac,aplanar undulator and a quasi-concentric optical resonator.The central frequency of the first saturated lasing was 2.56 THz,with the spectral width about 1.9%.The average output power in the macro pulse was larger than 5.7 W.