In the development of electric aircraft, the use of distributed electric propulsion introduces a potential occurrence of propeller whirl flutter, which needs to be taken into account for wing structural design. To this end, this work extends an in-house aeroelastic optimization tool by means of including a post-processing procedure on whirl flutter analysis. In aeroelastic optimization, propellers are modeled as concentrated masses, and the wing mass is minimized by tailoring the lamination parameters and thickness of wing laminates subject to aerostructural design constraints. For the whirl flutter analysis of the optimized wing, a new aeroelastic model is built by coupling propeller motions and aerodynamic loads into wing aeroelastic model. The usefulness of the purposed approach is demonstrated using a numerical example, where the required inputs on propeller mounting properties are determined via a parametric study. The result indicates that flexibly mounting propellers on a flexible wing leads to the decrease of wing flutter speed, and it also confirms that the propeller mounting properties have a large influence on aeroelastic instability of the coupled propeller-wing system.@en