Nominal predicate sentence is a superordinate space S composed of S₁(subject)and S₂(nominal predicate).A new exploration comes from linguistic topological study.The findings are as follows:there exists a topological invariance which remains offstage in the specific utterance because of the construal axis adjustment;the construal between S₁ and S₂ semantic default depends on mental and metonymy topology;the nominal predicate sentence derives from a verbal sentence and its position coercion endows verbal meaning on the nominal predicate;S endows verbal meaning on S₂ to ensure the continuity of the whole S and the smooth of construal;the pragmatic function bears both subjective scalar evaluation and the attitude towards the target.