The invention provides a flexible nitrogen-doped activated carbon composite electrode material and a preparation method thereof. The preparation method comprises the following steps that multiple cocoon shell sheets are stripped, then the low molecular weight phenolic resin compounding and high temperature activating treatment are performed, finally, the flexible nitrogen-doped activated carbon composite electrode material can be prepared. The carbon composite electrode material has high wettability, certain strength and flexible deformation ability, and the charge transmission property and the capacitive performance thereof are improved substantially.