For distributed electric propulsion (DEP) configuration, especially for distributed leading-edge propeller configuration, using traditional CFD calculation method, the coupling configuration grid of wing/ propeller will be very large, and the computational efficiency will decrease accordingly, which is not enough to support the fast calculation requirement in conceptual design stage. The traditional blade element momentum theory can only deal with the calculation state of the incoming flow vertical propeller disk, and the application scope is limited. By improving the traditional blade element momentum theory, this paper extends the traditional blade element momentum theory to two dimensions, so that it can deal with the condition that the incoming flow is not perpendicular to the propeller disk, and at the same time, it extends the application scope of the blade element momentum theory while ensuring the calculation efficiency. This paper provides a new calculation method for the conceptual design phase of distributed propeller propulsion configuration.