The invention provides an electrochemical capacitor-based liquid detection device, method and paper diaper, wherein the paper diaper comprises a dry and comfortable layer, a moisture absorption layer and a leakage-proof layer and also comprises at least two induction lines, power input ends and capacitance measurement ends, wherein each induction line can be directly contacted with urine to be detected the power input ends are respectively arranged on the induction lines and are used as ports used for injecting current into an electrochemical capacitor which consists of the induction lines and the urine and generating a specific bias voltage and the capacitance measurement ends are respectively arranged on the induction lines and are used as ports used for measuring direct-current capacitance under the specific bias voltage between the induction lines during the process of injecting the current into the electrochemical capacitor which consists of the induction lines and the urine through the power input ends and judging the urine-wet condition of the area in which the induction lines are located according to magnitude of the capacitance. According to the electrochemical capacitor-based liquid detection device, method and paper diaper, liquid detection and urine-wet detection can be accurately and reliably realized.
