Metal-organic framework (MOF) derived porous carbon materials have been widely applied as active materials for supercapacitors due to their large specific surface area and ordered pore structure. This paper presents a facile and effective strategy to regulate the morphology of a zinc-based metal-organic framework (Zn-trimesic acid, Zn-BTC) by adjusting the ethanol content in a solvent, which can effectively change the pore structure of Zn-BTC derived porous carbon (PC). The optimal PC prepared in 50% ethanol displays a rodlike structure with a large specific surface area (SSA) of 1930 m2 g-1 and an average pore size of 2.9 nm. This material shows an excellent rate performance with 78.8% capacitance retention when the current density increases from 1 A g-1 to 100 A g-1 and outstanding electrochemical stability with only 2.2% decline of capacitance after 200 000 cycles at 50 A g-1. Moreover, the assembled symmetrical capacitor shows a high energy density of 16.09 W h kg-1 at 698 W kg-1 and 11.89 W h kg-1 at a high power density of 41.56 kW kg-1. This method would provide a new pathway for the preparation of carbon materials with an adjustable pore size for high-performance supercapacitors.