Nonreciprocity and propagation of spin waves are key properties to develop spin-based electronics, such as magnetic memory, spin information and logic devices. To date, a nonreciprocity ratio cannot be manipulated in a system, while large values are achieved because of the geometrical magnetic configuration. In this study, we suggest a new magnetic system with two blocks, in which the nonreciprocity ratio can be changed between 0.276 and 1.43 by adjusting the excitation frequency between 7.8 GHz and 9.4 GHz. Because the two blocks have different widths, they have their own spin wave excitation frequency ranges. Indeed, the spin wave intensities in the two blocks, detected by the Brillouin light scattering spectrum, were observed to be frequency-dependent, yielding tunable nonreciprocity. Thus, this study provides a new path to enhance the application of spin waves in spin-based electronics.