The invention discloses a low-temperature condensate treatment process for a natural gas treatment plant deoiling and dewatering device. The process includes the following steps that 1, the temperature is increased to 29 DEG C after low-temperature condensate is preheated twice; 2, the low-temperature condensate is separated into gas-phase gas, alcohol-containing water and unstable gas condensate through a three-phase separator; 3, the alcohol-containing water is output to a methyl alcohol recycling device; 4, the unstable gas condensate enters a gas condensate stabilizing tower after being preheated and is heated to 142 DEG C at the tower bottom with conduction oil after being stabilized, the saturated vapor pressure reaches 70 kPa, the temperature is decreased to 40 DEG C after cooling is performed twice, and the stabilized gas condensate is output to a product tank field; 5, the gas-phase gas is mixed with tower top noncondensable gas to generate phase-change cooling, the temperature of the mixed gas is reduced to -10 DEG C, the mixed gas is subjected to low-temperature gas-liquid separation, the hydrocarbon dew point of fuel gas meets the quality requirement, and a liquid phase flows back to the top of the stabilizing tower. The invention further provides a device for implementing the process. Low-temperature separation of mixed gas is achieved under the condition that no external cold supply source is available, and thus investment is reduced; the requirement for cooling high-temperature gas condensate is met under the condition that an air cooler is omitted; besides, the energy of heat flow is reasonably utilized.