A dehumidifier includes a dehumidification system. The dehumidification system includes an air inlet, a cold energy storage, an evaporator, the cold energy storage, a condenser, and an air outlet for air to pass in sequence. The air inlet and the air outlet are disposed on a main body of the dehumidifier. The evaporator, the cold energy storage, and the condenser are fixedly mounted in the main body. The evaporator is used to cool the air so that moisture in the air is condensed into water droplets. A water tray is provided under the evaporator to collect the water droplets. The cold energy storage is disposed between the evaporator and the water tray for collecting the water droplets, absorbing cold energy and cooling the passing air. The condenser is used to heat the air to form dry air. The cold energy storage is to cool the air in advance, so that the moist and hot air becomes low-temperature and high-humidity air. The dehumidifier can reduce the power of the compressor, save energy, improve the dehumidification capacity, and improve the energy efficiency.