Large-sized chemical vapor deposited graphene films configured as solution-gated transistors can label-freely and electrically detect DNA hybridization with single-base specificity. The gate voltage which gives the minimum device conductance (V-g,V-min) is sensitive to the charge transfer between DNA molecules and graphene, and thus is used to detect the DNA hybridization. The DNA detection is attributed to the electronic n-doping from DNA to graphene rather than the electrostatic gating effect or impurity screening effect.