Abstract: 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.