The　differentiation　transforming　(DFT)　system　is　developed　to　produce　the　tangent　linear　codes,　which　is　used　to　calculate　the　Jacobian　and　the　Hessian-vector　products　with　no　truncation　errors.　This　paper　first　gives　the　introduction　of　the　functionality　and　features　of　the　DFT　system,　and　then　discusses　several　techniques　for　the　implementation　of　automatic　differentiation　tools,　including　data　dependence　analysis,　singular　differentiation　and　code　optimization.　Finally,　the　codes　generated　with　DFT　used　in　several　applications　have　been　demonstrated.　(C)　2008　National　Natural　Science　Foundation　of　China　and　Chinese　Academy　of　Sciences.　Published　by　Elsevier　Limited　and　Science　in　China　Press.　All　rights　reserved.