Abstract: A new parameter,D_par,which is the arithmetic mean etch figure diameter parallel to the C-axis at the etched surface,can describe effectively the annealing behavior of apatite fission tracks.Apatite grains from a single sample can be divided into different kinetic populations according to their measured D_par values.The time-temprature history modelling based on apatite fission track data can therefore be developed into a multikinetic modelling system consisting of several independent apatite thermochronmeters.Consequently,the modelling result is more practical and accurate.Four examples from different Chinese sedimentary basins are shown at the end of the paper.