This paper presents the specification language NUJSL and its supporting system.NUJSL is a modularspecification language based on Jackson Program Design Method(JSP).With the module construction,it isconvenient to use NUJSL to write larger specifications.The supporting system supports the incremental develop-ment of software specification in NUJSL,and implements the transformation both from specification tosoftware procedural description in Jackson Schematic Logic(pseudo code)and from procedural description toPASCAL program. This paper presents the specification language NUJSL and its supporting system. UNJSL is a modularspecification language based on Jackson Program Design Method (JSP) .With the module construction, it isconvenient to use NUJSL to write larger specifications. Supporting systems supports the incremental develop- ment of software specification in NUJSL, and implements the transformation both from specification tosoftware procedural description in Jackson Schematic Logic (pseudo code) and procedural description to PASCAL program.