Based on powder sintering technology, Yb3+/Al3+ codoped silica rods are prepared, and the concentration of Yb3+ is up to 12 000 ppm (wt). Then, with the Yb3+/Al3+ codoped silica rods as core materials, highly doped Largemodearea Photonic Crystal Fibers (LMAPCF) are fabricated by stackdraw method. The mode area can reach 550 μm2, and the mode field diameter is 26 μm. The results indicate that the fiber has a broad absorption band in the near infrared wavelength (850~1 033 nm), and the main peak is at the wavelength of 976 nm where the absorption loss is higher than 10 dB/m; when the fiber is pumped by the laser with a wavelength of 971 nm, there exists a Gaussian fluorescence peak in the wavelength range of 1 150~1 125 nm, with a peak value of 1 088 nm and a halfline width of 45 nm.