The principles of the splice loss between the germanium doped core photonic crystal fiber (PCF) and single mode fiber (SMF) at the wavelength of 1550 nm are investigated by the full-vector finite element method. The mismatch of mode field between the PCF and SMF is the main factor resulting in the high splice loss. The real structure profile is extracted to exactly simulate the splice loss due to the mismatch of mode field. Based on the arc fusion technique, a set of optimized fusion parameters are obtained from a series of experiments, and the repeat-discharge operation are used to make sure moderate collapse of the cladding air holes of the germanium doped core PCF. Then the mismatch of mode field could be reduced and the low loss splicing between PCF and SMF is realized.