On account of the problems existed preparing technology of large mode area Yb-doped PCF,drill getting core new techniques was application to remove the quartz skin of Yb doped core in this work.The new technology makes the processing precision and efficiency improved,Yb-doped core processing technical problems solved and Yb-doped area increased.Due to structure of PCF is instability,pressure control technology was adopted in this work to get the structural integrity and the rules of double cladding photonic crystal fiber.Finnally,rare-earth-doped photonic crystal fiber with 70 μm core diamter has been prepared successfully and realized the laser output.