In this work, we proposed a chevron-beam-based nonlinearity-tunable elastic metamaterial capable of tuning the nonlinear parameters. Instead of enhancing or suppressing nonlinear phenomena or slightly tuning nonlinearities, the proposed metamaterial directly tunes its nonlinear parameters, allowing much broader manipulation of nonlinear phenomena. Based on the underlying physics, we discovered that the nonlinear parameters of the chevron-beam-based metamaterial are determined by the initial angle. To identify the change in the nonlinear parameters according to the initial angle, we derived an analytical model of the proposed metamaterial to calculate the nonlinear parameters. Based on the analytical model, the actual chevron-beam-based metamaterial is designed. We show that the proposed metamaterial enables nonlinear parameter control and harmonic tuning by numerical methods.