The basic theory and common generation methods of vectorial optical fields are reviewed. The vectorial optical field generator based on spatial light modulator and its recent improvements in performances are introduced in detail. An overview of the vector diffraction theory under tightly focusing is offered, and the methods for tailoring the intensity distribution, polarization direction and spin orientation within the optical focal fields are highlighted. The applications of the tailored focal field in microscopy, directional coupling and so on are briefly discussed.