<p>The determination and prediction of cyclic shear dynamic strength in over consolidated clay foundations are crucial for the design of the horizontal bearing capacity of pile foundations. This paper conducts a series of undrained cyclic simple shear tests on remolded Wenzhou clay under various conditions of over consolidation ratio, vertical pressure and cyclic stress ratio. Combined with experimental data from four other clays, it is found that the dynamic shear strain and excess pore water pressure of over consolidated clay vary widely under cyclic shear. Hence, it is impossible to set a unified threshold for dynamic strength assessment. The occurrence sequence of four dynamic failure indicators is revealed as follows: the inflection point of the double-amplitude dynamic shear strain curve, the inflection point of the excess pore water pressure curve, the contact between the failure line and the stress path, and the attenuation of the shear stress amplitude. The differences between these occurrences become more pronounced with larger over consolidation ratio, lower vertical pressure or higher cyclic stress ratio. It is proposed that the derivative of double-amplitude dynamic shear strain curve reaching 30% serves as an improved criterion for determining the cyclic shear dynamic strength of over consolidated clay. Thus, the accuracy, universality and efficiency of the dynamic strength criterion can be achieved through the new “strain derivative method”. Finally, a convenient prediction method for the cyclic shear dynamic strength of over consolidated clay under various over consolidation ratio, vertical pressure and cyclic stress ratio conditions is established.</p>