A new pure logical language in clausal form was presented. The syntax, informal semantics, procedural interpretation of clauses and inference system based on constraint resolution were given. In this language, programs contain three types of variables:input variables, output variables and program variables to control resources of the computer; function symbols defined by programs can constitute terms or subterms and can be used as predicate symbols i the most general unification which is inefficient is not needed.According to these factors, programs implicate sequential, branched, iterative and recursive controls and it is easy to constitute efficient theorem-proving systems. It is believed that this language is a efficient, useful and practical, high-level, deterministic programming language with sound theoretical foundation.