We have fabricated a superconducting YBCO system according to the pyrolysis method and low pressure apparatus. In our experiment, the X-ray diffraction pattern of the non doped YBaCuO layer indicated that the superconductor contained only 90K phase crystal. The critical temperature and critical current density for a thick layer at $650^{circ}C$ were Tc=90 K and $Jc=6{ imes}10^{4}A/cm^2$ at 90K. In low pressure apparatus, the 90 K phase YBaCuO was grown at a lower temperature compared with the normal system. Tc and Jc at $650^{circ}C$ were Tc = 90 K and $Jc=6{ imes}10^{4}A/cm^2$ at 90K.