In this paper, we find travelling wave solutions for the fractional generalized Kuramoto-Sivashinsky equation. This equation arises in several problems of physics and chemistry. The fractional sub-equation method is used to construct the travelling wave solutions of the fractional generalized Kuramoto-Sivashinsky equation. As a result, the solutions obtained here are expressed in hyperbolic functions and trigonometric functions. Compared with other methods, this method is direct, concise, effective and easy to calculate, and it is a powerful mathematical tool for obtaining exact travelling wave solutions of other nonlinear fractional partial differential equations.