We study numerical methods for porous media equation (PME). There are two important characteristics: the finite speed propagation of the free boundary and the potential waiting time, which make the problem not easy to handle. Based on different dissipative energy laws, we develop two numerical schemes by an energetic variational approach. Firstly, based on f log f as the total energy form of the dissipative law, we obtain the trajectory equation, and then construct a fully discrete scheme. It is proved that the scheme is uniquely solvable on an admissible convex set by taking the advantage of the singularity of the total energy. Next, based on 1 2f as the total energy form of the dissipation law, we construct a linear numerical scheme for the corresponding trajectory equation. Both schemes preserve the corresponding discrete dissipation law. Meanwhile, under some smoothness assumption, it is proved, by a higher order expansion technique, that both schemes are second-order convergent in space and first-order convergent in time. Each scheme yields a good approximation for the solution and the free boundary. No oscillation is observed for the numerical solution around the free boundary. Furthermore, the waiting time problem could be naturally treated, which has been a well-known difficult issue for all the existence methods. Due to its linear nature, the second scheme is more efficient.The porous medium equation (PME) can be found in many physical and biological phenomena, such as the flow of an isentropic gas through a porous medium [18], the viscous gravity currents [12], nonlinear heat transfer and image processing; e.g., see [33]. The aim of this paper is to provide numerical methods for the PMEwhere f := f (x, t) is a non-negative scalar function of space x ∈ R d and the time t ∈ R, the space dimension is given by d ≥ 1, and m is a constant larger than 1.The PME is a nonlinear degenerate parabolic equation since the diffusivity D(f ) = mf m−1 = 0 at points where f = 0. In turn, the PME has a special feature: the finite speed of propagation, called finite propagation [33]. If the initial data has a compact support, the solution of Cauchy problem of the PME will have a compact support at any given time t > 0. In comparison with the heat equation, which can smooth out the initial data, the solution of the PME becomes non-smooth even if the initial data is smooth with compact support. If an initial data is zero in some open domain in Ω, it causes the appearance of the free boundary (in some cases, called interface) that separates the regions where the solution is positive from the regions where the value is zero in the domain. Moreover, for certain initial data, the solution of the PME can exhibit a waiting time phenomenon where the free boundary remains stationary until a finite positive time (called waiting time).After that time instant, the interface begins to move with a finite speed. Many theoretical analyses have been available in the existing literature, including the earlier works by Oleǐnik et al. [25], Ka...