The crazing damage and fracture process of polymers is very complicated and important. The thermodynamic or mechanical conditions and micromechanisms of craze initiation in polymers are briefly introduced in this paper. The recent advances in experimental studies and model computations, the meniscus instability mechanism for craze-tip advance, the creep mechanism and surface-drawing mechanism for craze thickening are discussed in detail. The cross-tie fibrils in craze microstructure, the relations between the molecular weight, entanglement density and the craze fracture behavior and the interaction between craze and crack growth are extensively reviewed. It is pointed out that the further studies on craze growth and breakdown can be expected to relate the macroscale fracture toughness, mesoscale structures and microscale material parameters, thus provide guidance to design the material toughness at microscale level. Meanwhile, the further study and development trends of this field are also outlined.