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A quasi-Bessel beam is a type of nondiffracted beam commonly used in microwave and optical fields. Although numerous methods have been proposed for quasi-Bessel beam generation, they are valid only in linear systems, indicating that the generation of nonlinear quasi-Bessel beams remains a major challenge. Thus, we propose a new approach to produce quasi-Bessel beams at high-order harmonics based on the time-domain digital-coding metasurface, which is utilized to achieve accurate control of the phase profile at the nonlinear frequencies via proper coding strategies. The effect of phase discretization is also analyzed in detail. The simulation results confirm the validity of the proposed method, which provides a new approach for nonlinear beam manipulation.