By liquid pipe, tanks, water film and evaporation hole components. It capillary action and atmospheric evaporation water-absorbing film is combined as a driving force. Within the general range of temperature and humidity fluctuations of the same working day, the micro-pump provides a stable μL / min flow rate of the liquid level in a long time. By changing the area of the hole or evaporation using a fan to adjust the flow rate of the micropump. Micro-pump flow rate accuracy is generally better than 3% This micropump simple, low cost, small size, flow rate stable, long continuous use and easy to adjust the flow rate, with no external energy, the running time is not limited to any length (relative humidity of <100%) of the advantages.