Abstract: PDL is a method which is widely used for software detailed design in CASE.JS-PDL/C is an interactive, multi-window and menu driven software detailed designtool based on PDL method in the software development environment JS-CASE. It translates structure charts and module specifications in the concept design stage into the initial detailed design documents, and then, by editing, stepwise refining and using a partially automatic transfer, generates the C programs and detailed design documents. Thispaper introduces some basic concepts of JS-PDL/C, and discusses its design and implementation.