In this paper, a new type of multiway height balance trees-Compact (a, b) tree is presented. In such a tree, the nearly optimal storage utilization and nearly optimal height are guaranted by intruducing a constrain between number of children and gradchildren with a Reorganize operation. It s seach opertion is quicker than the B*-trees and B-trees. It s update operations (insert, delete) are the same performance as B-trees on the amortized computational complexity.