The invention discloses a charge-coupled device with a multi-well structure and a preparation method of the charge-coupled device. The epitaxial layer is arranged on the substrate; the composite well region is arranged on the epitaxial layer and comprises a first well, a second well and a third well, and the first well and the third well form a
saddle point in the center of a pixel, so that well
doping below a CCD pixel unit needs to be weaker than that on the two sides, a weak
doping channel of the composite well region is formed, and the composite well region is used for a charge-coupled device to
discharge excess charges; the CCD charge channel is arranged on the composite well region; the channel resistors are arranged on the composite well region, located on the two sides of the CCD charge channel and used for achieving isolation of the CCD charge channel between different unit columns of the charge-coupled device; the
dielectric layer is arranged on the upper surfaces of the CCD charge channel and the channel
resistor; and the
polysilicon gate is arranged on the upper surface of the
dielectric layer and is used as a functional
electrode of the charge-coupled device. Therefore, the CCD device has the capability of discharging excess charges.