We present a power-free droplet generator microdevicecapable of the production of monodisperseddroplets driven byair-evacuated PDMS.Compared to current droplet-based microfluidic devices,the developed droplet generator circumvents the external power equipments and eliminates the cumbersome tube connection.The only operation for end-users is to put a drop of the aqueous sample and the oil into the different chip port respectively,and then thousands ofmonodisperseddroplets could be generated automaticallyin a few minutes.The CSV of the droplet size is 2.4%.Thisdeveloped power-free droplet generator could be easily integrated into different kinds of portable devices for on-field applications.