Abstract: The problem of clamping balance is a typical issue of the multi - rigid - body balance analysis in theoretical mechanics.Based on the knowledge of static mechanics，the equilibrium conditions for clamped multiple blocks in parallel plates are discussed.The force analysis of a single block shows that the line position of the equivalent concentrated force on both sides of the block presents a ladder - like symmetry distribution. Then the critical pressure needed to maintain the balance of the system is discussed for different situation.

Key words: clamping balance, non - collinear, ladder - like symmetrical distribution, critical pressur