Er∶CNGG crystals with the doping concentration （atomic fraction） of 0.3%， 2.0%， 3.0% and 5.0% were grown by the micro-pulling-down method. The crystal structure was tested by X-ray diffraction （XRD）， and the results show that the crystal structure is cubic. The absorption spectra， fluorescence spectra and fluorescence decay curves of Er∶CNGG crystals were measured at room temperature. The absorption coefficient of 5.0% Er∶CNGG crystal is 1.70 cm^-1 at 968 nm， with a full width at half maximum （FWHM） of 17.5 nm， which matches well with the commercial laser diode pumping sources. The strongest emission peak of 5.0% Er∶CNGG crystal is located at 2 709 nm with FWHM of 17.3 nm. The lifetime of ⁴I_13/2 energy level of 0.3%， 2.0%， 3.0% and 5.0% Er∶CNGG crystals are 5.97， 6.30， 6.46 and 5.73 ms， respectively. The results show that Er∶CNGG crystal is a potential gain medium for laser at around 2.7 μm.