Abstract
In this article, we use fractional sub-equation method to find the exact solutions for some nonlinear partial fractional differential equations, namely space-time fractional coupled Sakharov-Kuznetsov (Z-K) equations, space-time fractional nonlinear coupled Korteweg de Vries (KdV) equations and space-time fractional Hirota-Satsuma KdV system. As a result, three families of exact analytical solutions are obtained. Proposed method is more effective and powerful to construct the exact solutions for nonlinear partial fractional differential equations. Also, we use fractional complex transform and exp function method to find some of the exact solutions for nonlinear partial fractional differential equations.