In this paper, we proposed a label-free and high-sensitive detection method of circulating tumor DNA (ctDNA) mutations using QCM(quartz crystal microbalance). We detected the ctDNAs by evaluating the resonance frequency shift of QCM electrode upon DNA hybridization between probe DNA and ctDNA. When probe DNAs capture target DNAs through DNA hybridization, the resonance frequency shift occurs due to mass change of electrode of QCM. In situ, high sensitive, and label-free detection of ctDNAs could achieved using QCM. The platform is able to sense ct DNA with a limit of detection (LOD) of 1.0 nM.