The traditional toggle mechanisms occupy a large building space，and the current mechanism analysis on its time-variant displacement amplification ability is not complete. In view of the above shortcomings，a generalized toggle mechanism（GTM）is proposed，which occupies a small space and is flexible in layout. The traditional toggle mechanism can be regarded as a special case. Based on the change rule of the displacement increment amplification coefficient of GTM，the corresponding comparison criteria and simplified parameters of the displacement amplification capability are proposed，and a generalized toggle mechanism geometric parameter optimization method based on the premise of reasonably determining the limit of the available side displacement of the toggle joint is proposed. The relationship between the displacement amplification capability of GTM and energy consumption is clarified. The method for calculating the additional equivalent damping ratio of GTM is proposed，and a design method of GTM for multilevel seismic performance fortification is proposed by combining the time-varying damping ratio and the toggle geometry optimization. The validity and feasibility of the design method are verified by analysis of examples.