Abstract:Fracture spacing is an important fracturing phenomenon in crustal rock formation and geotechnical engineering structures,but its formation mechanism is not clear. Fracture spacing in stratum,earth shrinkage and fracture spacing(zonal disintegration) in rock mass around deep tunnel all belong to fracture spacing. And fracture spacing in concrete structure,shrinkage crack on ceramics driven by cooling and drying and so on are typical models of fracture spacing. Based on the background,the results of numerical tests on mechanism and evolution laws of fracture spacing are put forward with RFPA. Three patterns of fracture spacing are:(1) parallel fracture spacing(parallel crack),(2) net fracture spacing(crack),(3) ring fracture spacing(zonal disintegration).