A new computation model of programming language，function model with iteration operator was presented．The syntax of language based on the model，the set of computation rules and a proof of determinism were given．In this language，sequence is expressed by composition of expressions，branch by condition expressions and iteration by iterative expressions．such that its programs are based on mathematical semantic founda-tion，easy to understand，prove its correctness and constitute efficient execution system． The authors believe that this language is an efficient，useful and practical，high—level de- terministic programming language with sound theoretical foundation．