In this paper, the first-principles method based on density functional theory and non-equilibrium Green’s function is used to design and investigate the transport properties of multifunctional spintronic devices based on zigzag SiC nanoribbon via edge asymmetric dual-hydrogenation. The zigzag SiC nanoribbons via edge asymmetric dual-hydrogenation are selected as electrodes, and SiC atomic single chains are connected to the above, upper-middle, lower-middle, and below the positions of the electrodes to form four molecular devices: M1, M2, M3 and M4. In this study, it is found that the maximum spin current value of the device in the P-magnetic configuration decreases sequentially with the connection position transitioning from top to bottom. The spin-down current-voltage curves of M1, M2, and M4 exhibit significant spin rectification effects, with maximum rectification ratios of 9.8×10⁵, 5.2×10⁵, and 6.7×10⁴, respectively. The spin-up current-voltage curve of M3 shows the best rectification effect, with a maximum rectification ratio of 6.9×10⁶. More importantly, the spin-up current-voltage curve of M3 exhibits a unique negative differential resistance effect in the negative voltage range. In the AP magnetic configuration, the spin-up currents of the four devices are very weak throughout the bias region and hardly changes with the increase of voltage. Although there are differences in the spin-down current between the four devices within the positive and negative bias ranges, they are not significant, thus failing to demonstrate excellent rectification effects. In addition, M2 exhibits perfect spin filtering effect in the negative voltage range in both P and AP magnetic configurations, with a spin filtering efficiency close to 100%. This work integrates spin rectification and spin filtering, as well as spin rectification and negative differential resistance, into a single molecular device, achieving the theoretical design of a composite spin device with two functions. The research results provide an important solution for practically preparing and controlling zigzag SiC nanoribbon spin devices in the future.