In this paper, Er:Ca4YO(BO3)(3) (Er:YCOB) and Er:Yb:Ca-4 YO(BO3)(3) (Er:Yb:YCOB) crystals with large size and excellent quality have been grown by the Czochralski method. The absorption and emission spectra of Er:YCOB and Er:Yb:YCOB crystals have been measured; the emission spectrum of Er:Yb:YCOB crystal shows that the strongest emission peak is located at 1537 nm. An output power of about 2 mW at the wavelength of 1553 nm has been obtained under the pumping power of a fiber-coupled laser diode (LD) of 1600 mW at 976 nm, using a Y direction cut 2.5 mm thick Er:Yb:YCOB crystal sample.