The cascadic multigrid method for the second order elliptic problem is considered, which is discretized by P1 nonconforming element, or Carey element, or Wilson element, is accurate and has the optimal complexity.

• 证明了两阶椭圆边值问题的cascadic多重网格方法 ；对于P1非协调元、Carey非协调元、Wilson非协调元均可以达到最优 .