<正>In this paper the ionosonde data from 16 stations all over the world were used to analyze the morphological features of occurrence rate of spread-F, i.e. their regional distributions and variations with seasons and solar cycles. The statistical results showed that the stations with nearly the same geographic locations but different geomagnetic inclinations or declinations have different occurrence rates of spread-F and thus indicated the significance of geomagnetic configurations in the formation and evolution of spread-F. The occurrence rate is the lowest in a region in mid-latitude and it is asymmetric in the northern and southern hemispheres. In mid-latitude, obvious solar cycle can be seen while it is to the contrary in other regions. The data analysis results agree well with theoretical ones.