A miniature liquid cooling device includes a casing (10) defining a first chamber (102), a second chamber (104) and a third chamber (106) communicating with the first chamber. The first and the third chambers cooperatively form a work channel for liquid. An impeller (21) is rotatably mounted in the first chamber to circulate the liquid. A filter (17) is mounted in the second chamber and defines a plurality of orifices (1704). When the impeller rotates the liquid firstly enters the second chamber via an inlet (122) and flows through the filter, whereby air bubbles in the liquid leave the liquid and escape from the filter via the orifices. The escaped air bubbles enter the second chamber. The deaerated liquid flows into the work channel and finally is driven to flow out of the liquid cooling device via an outlet (124).