We present a new approach depending on reproducing kernel method (RKM) for timefractional Kawahara equation with variable coefficient. This approach consists of obtaining an orthonormal basis function on specific Hilbert spaces. In this regard, some special Hilbert spaces are defined. Kernel functions of these special spaces are given and basis functions are obtained. The approximate solution is attained as serial form. Convergence analysis, error estimation and stability analysis are presented after obtaining the approximate solution. To show the power and effect of the method, two examples are solved and the results are given as table and graphics. The results demonstrate that the presented method is very efficient and convenient for Kawahara equation with fractional order.Fractional concept as a branch of mathematics investigated integration and derivatives for non-integer order. As of late, this concept has become an attractive field because of its significant researches and applications such as heat conduction, diffusion wave, dynamical system, oil industries, signal processing, cellular system and other subjects. These subjects Communicated by José Tenreiro Machado.