Abstract: The present invention discloses a method and system for a wind stress coefficient expression by comprehensively considering impacts of an average wind speed, a fetch and a water depth, and relates to the field of wind-wave-current numerical simulation studies. Based on a wind-wave-current coupling interaction mechanism in lakes, oceans and other waters, two dimensionless numbers that can represent a wind-wave-current interaction strength: a fetch Froude number and a fetch Reynolds number, are constructed, a form of a wind stress coefficient expression with an undetermined coefficient is established, and then the undetermined coefficient is obtained by using a nonlinear regression method with reference to experimental and measured data to obtain a final wind stress coefficient expression.