For scanning near-field optical microscopy (SNOM), the taper shape of the fiber probe remarkably affects its transmission efficiency. According to the local mode theory, transmission efficiencies of the conical and the parabolic probes are analyzed respectively, and characteristics of the efficiencies versus geometrical parameters of the fiber taper are also discussed. Both theoretical and experimental results show that the transmission efficiency of the parabolic probe is much higher than that of the conical probe.