Coming across an article on the present status of hepatitis C in China, we are shocked at the relatively high mortality rate and magnitude of the epidemic. Unfortunately, there is currently no vaccine for hepatitis C though research in this area is ongoing. Due to the fact that HCV infection is usually asymptomatic, few people are diagnosed during the acute phase, while among those people who go on to develop chronic HCV infection, the infection is also often undiagnosed until decades later when symptoms develop from secondary to serious liver damage.Thus, the need for effective early-stage diagnosis methods is urgent. However, due to complex testing procedures and expensive equipment required, the promotion of current diagnostic methods is hindered.Witnessing such a situation, we seek to create a new type of low-cost and high-sensitivity testing method to be applied in military and humanitarian aid field operations, especially in developing countries. Inspired by Olivia Hallisey's invention in 2015--Detection of Ebola via a Silk-Derived Lateral-Flow System and Mr. Keith Pardee's article about Paper-Based Synthetic Gene Networks(Keith Pardee, 2015),we came up with the idea of designing a test paper to contribute to HCV detection via synthetic biological method. We create cell-free systems on paper with the fundamental transcription and translation properties of a cell. The core of the cell-free system we have created on paper is a plasmid, which consists of a strong promoter, a toehold switch and a downstream reporter gene, functioning as a biosensor. The toehold switch, which uses base pairing to the RBS to prevent ribosome binding, is unwound upon binding of a cognate trigger RNA, exposing the RBS and enabling translation of the downstream protein. The expression of reporter gene (lacZ) enables qualitative and semi-quantitative assay of HCV. Once we are able to put the test paper into production, more regions in the world can be covered with the advanced detection method to fight against HCV. Moreover, we hope that the synthetic biological detection method can be applied to the diagnosis of other viral diseases by changing the sequence of the toehold switches in the future.