Abstract: When the pre-clearing result of an electricity spot market could not meet all the security constraints due to inappropriate boundary condition settings or other reasons, the necessary security correction measures should be implemented. This paper proposes a generation scheduling correction method to eliminate security violations. The security correction is first applied to the non-market units to get the feasible solution which meets all the security constraints. Then the final clearing result is obtained by the optimization of market units. The theory of steady-state security region（SSR） is applied to the non-market unit correction, and the ramping constraints are included in the description of the SSR boundary. The optimal correcting direction could be revealed by the vector of steady-state security distance（SSD）. And the effectiveness that each unit eliminates security violations could be evaluated based on the sensitivity of security distance and the regulating ability of the unit. Based on this, the generation scheduling correction decision-making method is proposed, and the influence of the correction in each time interval on the SSD of the adjacent time interval is considered during the calculation procedure. Thus, the effect of correction optimization is improved. Based on the IEEE 118-bus system, the correction results and the influence of security constrain limits and unit ramping ability on security correction are analyzed, which prove the effectiveness of the proposed method.