The invention provides an expanded perlite hydrophobic system for a liquefied natural gas (LNG) carrier, belonging to the technical field of heat-insulating materials. The expanded perlite hydrophobic system is composed by two sets of parallel input devices and nozzles which are connected with the input devices, wherein the input device comprises a gate valve, a reducing valve, a Y-type filter, apressure gauge, a proportioning pump, a hydrophobic agent liquid storage tank, a solution pump and a mixed liquid storage tank. According to the invention, an automatic control device is used to adjust the ratio of the hydrophobic agent mixed liquid and automatically control the flow, the injection speed and the atomizing degree of the hydrophobic agent mixed liquid, so that hydrophobic-type expanded perlite can be produced with stable and reliable quality and high output and can be widely applied to temperature zones. The expanded perlite hydrophobic system can not only satisfy the heat-conducting property of the hydrophobic-type expanded perlite for an LNG carrier, but also ensure the hydrophobic performance of the hydrophobic-type expanded perlite in the damp environment.