By incorporating the dispersive permeability of metamaterial into the nonlinear polarization component, and borrowing the derivation way of nonlinear pulse propagation equation in ordinary material, a general nonlinear propagation equation for ultrashort pulse in metamterial is obtained. It is shown that for Drude dispersive model, the dispersive permeability results in a self-steepening parameter which can be negative, positive or zero depending on the central frequency of the pulse, and a series of high-order nonlinear dispersion terms in the propagation equation. Furthermore, the propagation equation is analyzed by using the moment method, an explicit expression for energy conservation for the propagation equation is obtained, and unique propagation properties of ultrashort pulse in metamaterials are disclosed. It is found that due to the second-order nonlinear dispersion, the characteristic parameters of the ultrashort pulse, including energy, frequency shift, duration, center position, and chirp, all oscillate with propagation distance.