The invention discloses a capacitor having a dendritic electrode structure. The capacitor comprises surface electrodes attached to both sides of a base film, wherein a plurality of dendritic electrodes are disposed in the base film have their roots connected to the surface electrodes. Compared with the comb electrode structure of a specific microcapacitor, the dendritic electrode structure is reduced in width to tens of nanometers, increases the relative change amount of sensitive capacitance, and improves the performance of a sensor. Compared with the existing microcapacitor electrode structure, the dendritic electrode structure greatly increases the contact area between the electrode and a dielectric, and improves the sensitivity of a microcapacitive sensor. Due to the flexibility of thebase film material, the dendritic electrode structure is also suitable for a flexible microcapacitor. The capacitor is simple in structure and the process is easy to operate. The electrode structureof the microcapacitor is miniaturized, and is suitable for detecting physical quantities such as pressure, displacement, gas concentration, and the like, has good practicability and wide applicability, and can be made into a humidity sensor with excellent performance especially when using a Nafion film as the base film.