In view of the growing demand for clear energy, the development of nuclear reactors with enhanced heat exchange efficiency has become an imperative necessity. In this research, the closed parallel longitudinal sinusoidal wavy narrow channels were proposed to enhance the turbulent mixing and heat transfer of the heat exchange components in nuclear reactors. A physical model, comprising two longitudinal sinusoidal wavy main channels (channels 1 and 2) and 24 cylindrical connecting channels, was established as the research object. To investigate the turbulent mixing characteristics of the proposed channels, numerical simulations were performed using the k-epsilon turbulence model. The simulations were conducted under varying mass fluxes (G = 500 kg/m2s or 3000 kg/m2s) and diverse heating conditions (equal or unequal heat fluxes). The results indicate that the left connecting channels demonstrate a net flow from channel 1 to channel 2, whereas the right connecting channels exhibit a reverse flow. The maximum turbulent mixing mass flow rate at G = 500 kg/m2s and G = 3000 kg/m2s is approximately 0.343% and 0.367% of the mainstream mass flow rate, respectively. Furthermore, the turbulent mixing factor was defined to evaluate the turbulent mixing characteristics of the proposed channels. At G = 500 kg/m2s, the unequal heat fluxes exert a considerable influence on the turbulent mixing effect. At G = 3000 kg/m2s, the turbulent mixing factors are higher, leading to a more intense turbulent mixing effect. The findings of this research are expected to provide ideas and references for further investigation in the design and optimization of the heat exchange components in nuclear reactors.