Research on hierarchy of large-scale software macro-topology plays an important role in comprehension and control of software Architecture structure.In this paper

we find that the large-scale software hierarchical structures are flat and relative stable based on a large number of statistics data on coreness of open source software structures

and argue the rationality of analyzing the large-scale software structure hierarchy using the means of

k

-core.On this basis

we use a version of Eclipse 3.4.2 as empirical analysis

divide it into layers

and analyze the internal and external connected relation

then argue the topology characteristics of the high-layer regions and low-layer regions.Finally

we use several versions of Eclipse as empirical analysis to study the evolution of highest layer form some aspects as network scale

degree distribution

an

d small-world characteristic.