Software system complexity has increased continuously with the promoting of users requirements.Therefore

how to keep robustness and correctness of large-scaled complicated software system has gradually become a hot issue

and study on uncertainty semantics computation is the key solution to this question.By analyzing the relevant study work

this paper makes a model of uncertainty semantics computation

designs four kinds of different formal semantics for a small typical language

and also proves the correctness and flexibility of this model by proof of equivalences for four kinds of formal semantics.