A new method for digital network logic analysis-reasoning approach is presented in this paper. In this approach the problem of logic analysis is considered as a problem of an automatic theorem proving

that is

all the knowledge of the basic logic networks

the network topology of the simulated logic and the input signal sequences are all considered as axioms

lemmas or predefined assertions

and the output signals to be found are the new assertions implied in all the premises

the process of a logic analysis is just the process to infer the new assertions （theorems） from the axioms

lemmas.The principle of the reasoning approach and the reasoning procedure for logic analysis are introduced in detail in this paper. A comparison between the new approach and the traditional logic simulation methods has also been made.