A miniaturized liquid cooling device (200) includes a heat absorber (20), a heat dissipater (30), a droplet generator (40) driving a working fluid circulating between the heat absorber and the heat dissipater, and a plurality of tubes (50) connecting the heat absorber, the heat dissipater and the droplet generator with each other. The droplet generator includes a bottom electrode plate (42), a top electrode plate (44) hermetically covering the bottom electrode plate, a fluid channel (425) formed between and a plurality of control electrodes (422) disposed between the top electrode plate and the bottom electrode plate. The control electrodes are arranged between an inlet (481) and an outlet (491) of the droplet generator. Voltages are regularly applied across the control electrodes so as to generate a plurality of fluid droplets (D) and drive the fluid droplets to move from the inlet towards the outlet of the droplet generator.