A liquid cooling device includes a liquid cooling conductor, a detecting probe, and a determining circuit. The liquid cooling conductor includes a chamber defined therein for communicating with the outside, the chamber is configured to accommodate the coolant, and the surface of the liquid cooling conductor is provided with at least one communicating port communicating with the chamber; wherein the liquid cooling conductor is formed joining at least two combination blocks, and at least one of the two combination blocks is a metal conductor. The detecting probe is disposed on the liquid cooling conductor and normally electrically disconnected from the metal conductor. The determining circuit is electrically connected to the metal conductor and the detecting probe, and generates a liquid leakage alarm signal when the metal conductor and the detecting probe are electrically connected.