Abstract: The paper presents an extension multi-layer perceptron model that is capable of representing  and reasoning propositional knowledge base．An extended version of propositional calculus is developed    and its some properties is discussed．Formulas of the extended calculus can be expressed in the extension  multi-layer perceptron ．Naturally   semantic deduction of propositional knowledge base can be imple- ment by the extension multi-layer perceptron  and by learning  an unknown formula set can be found .  

Key words: multi-layer perceptron, extension multi-layer perceptron, propositional calculus, proposi- tional knowledge buse, semantic deduction