中文摘要：

Estrada等人于1998年提出了原子键连通性指标,简称ABC指标。该指标已被广泛应用于研究烷烃的稳定性以及环烷烃的应变能等。通过对边的分类计算,得到自由边界条件下的两类网格图（即8.8.4格子和8.8.6格子）的ABC指标的精确表达式。

英文摘要：

The recently introduced atom-bond connectivity index, which is abbreviated as ABC index and was proposed by Estrada et al in 1998, has been applied to study the stability of alkanes and the strain energy of cycloalkanes. In this article, the ABC indices of two types of lattices on free boundary condition are obtained by the classification of all the edges of 8.8.4 and 8.8.6 lattices.