In this work, we find a regulation of electric powergeneration of static statefuel cells. This regulation is described as: Total electric power of static statefuel cells is proportional to the square of potential difference between thermodynamic equilibrium potential and export potential. With this regulation we derive an equation to describe the performance curve of static state fuel cells. There are two main parameters in the equation: one is power convert coefficient of fuel cell: K; another is fuel cell inner resistant: R. With these parameters, we can evaluate fuel cell more clearly and easily. The equation is verified with different kinds of direct methanol fuel cells and gives out the capacity of fuel cell is related to the inner resistant and chemical reaction. This regulation is also fit to fuel cells in series and parallel group. (C) 2003 Elsevier Science B.V. All rights reserved.