Focal shift plays an important in many optical fusing systems. In this article, focal shift of concentric piecewise
cylindrical vector beam is investigated by means of vector diffraction theory in detail. The section of the beam consists
of three concentric zones. The center circle zone and outer annular zone are radial polarized, and the inner annular zone
is generalized polarized. In addition the wavefront phase distribution of the vector beam is linear function to radial
coordinate. It is found that the parameter in phase distribution induces focal shift and can alter focal shift considerably.
However, radii of the inner annular zone and polarization angle do affect focal shift very slightly. So the phase parameter
can be used to alter big focal shift while the radii and polarization angle may be employed to adjust intensity distribution.
In focusing system, the focal shift and intensity distribution may be controlled separately, which improves the
application freedom of this kind of technique. Focal shift direction can also be altered by change the phase parameter.