Abstract: By means of stress-strain feature of upper and lower strata of fold neutral plane in the course of longitudinal fold formation,the differences between the upper coal bed and lower coal bed of fold neutral plane are analyzed from the coal thickness,coal structure,coal body structure,coalbed gas occurrence and diversities etc.,revealing the cause of these appearances.The investigation provides theory basis for forecasting coal thickness,coal bed structure,and coal and gas outburst in fold area.