While the classical discontinuous deformation analysis (DDA) is applied to the analysis of a given block system, one must preset stiffness parameters for artificial springs to be fixed during the open-close iteration. To a great degree, success or failure in applying DDA to a practical problem is dependent on the spring stiffness parameters, which is believed to be the biggest obstacle to more extensive applications of DDA. In order to evade the introduction of the artificial springs, this study reformulates DDA as a mixed linear complementarity problem (MLCP) in the primal form. Then, from the fact that the block displacement vector of each block can be expressed in terms of the contact forces acting on the block, the condensed form of MLCP is derived, which is more efficient than the primal form. Some typical examples including those designed by the DDA inventor are reanalyzed, proving that the procedure is feasible. discontinuous deformation analysis, contact and impact, complementarity theory, non-smooth analysis, open-close iteration Citation:Li X K, Zheng H. Condensed form of complementarity formulation for discontinuous deformation analysis. Sci China Tech Sci, 2015, 58: 1509 1519,