In this paper,theoretical and technical development of coherent anti-Stokes Raman scattering (CARS) microscopy is reviewed. The requirements of CARS microscopy on the pump laser source and typical experimental instrumentation are discussed and compared. We investigate the non-resonance background noise which is the most critical problem and can not be avoided in the CARS microscopy. Different methods for suppressing non-resonant background noise are presented and compared. Finally,a brief analysis of existing problems in CARS microscopy and possible solutions is presented.