Inthispaper,nonexactfractionalFouriertransformrelationbetweenobjectplaneandtransformplane,whicharearbitraryplaneofbothsidesoflens,isquantitativelyobtainedbyuseofFresneldiffractionequation.intensitydistributionontransformplaneisidenticalwithintensitydistributionofexactfractionalFouriertransformonsameplane.ComparingwithexactfractionalFouriertransformcomplexamplitudedistributionhasphasechange.Relationbetweentransformorderanddistancefrombothplanestolensisalsoobtainedquantitatively.