Long and tortuous pores in granular porous carbons for supercapacitors result in inferior rate capability and low capacitance. Sheet-like porous carbons with short pore length show potential applications as supercapacitor electrode materials. Herein, wrinkled porous carbon nanosheets (WPCNSs) were prepared from methyl naphthalene oil using CaCO3 template coupled with in-situ KOH activation strategy. The WPCNS features wrinkled sheet-like architecture with abundant short pores. The WPCNS electrode shows a high capacitance of 286 F g(-1) at 0.05 A g(-1), a good rate capability of 201 F g(-1) at 20 A g(-1), and an outstanding cycle stability with 98.4% initial capacitance after 7000 cycles in KOH electrolyte. This work provides a feasible method to prepare WPCNSs from aromatic liquid carbon precursors using low-cost CaCO3 as template for high-performance supercapacitors.