The invention discloses a precise adjustable liquid expansion temperature controller, and the controller comprises a switch assembly and a liquid closed power system arranged on the switch assembly and used for generating switch driving quantity matched with a switch. According to the precise adjustable liquid expansion temperature controller, through the liquid intangibility and uniform moleculardistribution, the temperature is sensitive to temperature changes, the volume expansion coefficient is high, and an elastic energy conversion diaphragm capsule is combined, so the tiny change of thetemperature can be converted into a corresponding displacement and force; a temperature control probe is directly contacted with an equipment working environment, and no indirect energy transmission component is arranged in the middle; the temperature is converted into a temperature variable (heat energy) by the diaphragm capsule and is directly applied to the switch contact assembly; by means ofthe structure, tiny temperature changes of the control environment can be converted through the diaphragm capsule and transmitted to the switch assembly, so the problem of energy inconsistency causedby energy transmission loss in the liquid expansion temperature control process and part deviation is solved, the one-to-one relation of energy transmission is achieved, precise temperature control over equipment is achieved, and better use prospects are brought.