[Objective] To address the issues of large generator-side torque ripple and significant DC-bus voltage fluctuation in small off-grid vertical-axis wind turbine systems under variable wind speeds and load disturbances, a cooperative control strategy based on super-twisting algorithm direct torque control, space vector pulse width modulation (STA-SVPWM-DTC), and DC/DC voltage regulation is proposed, which simultaneously suppresses torque ripple and stabilizes the DC-bus voltage. [Methods] A hierarchical decoupling control approach was adopted, dividing the system into two main modules: generator-side rectification and DC-link voltage stabilization. For the generator-side control, a composite sliding manifold was constructed using stator flux error and electromagnetic torque error. A super-twisting sliding mode control (STSMC) was utilized to output a continuous and smooth control signal, which drove the generator-side PWM rectifier via SVPWM, thereby eliminating the high-frequency torque ripple caused by the hysteresis-based discrete switching in conventional DTC. On the DC-link side, a dual-loop DC/DC voltage regulation architecture was built with a voltage outer loop cascaded with an inductor current inner loop. An independent voltage regulation loop was used to block the transmission of load-side power fluctuations to the generator side, attenuating the reverse coupling interference between the two control channels. [Results] To verify the performance of the proposed strategy, multiple sets of simulation conditions and physical load experiments were set up for comparative testing. Under the step wind speed condition where the wind speed decreased from 12 m/s to 7 m/s, simulation results showed that, compared with the conventional DTC, the proposed STA-SVPWM-DTC and DC/DC coordinated control method reduced the peak-to-peak electromagnetic torque from 1.35 N·m to 0.4~0.5 N·m, a decrease of 60~70%. Under step wind speed, combined wind speed, and 10 Ω load experimetal conditions, the DC bus voltage was stabilized near 12 V, and the voltage and current ripples were significantly reduced. [Conclusion] The proposed STA-SVPWM-DTC and DC/DC coordinated control strategy improves the torque smoothness and DC output stability of small off-grid vertical-axis wind power systems, and provides a feasible control scheme for the stable operation of off-grid wind power supply systems.