A process for continuously producing polyoxymethylene dimethyl ether at low temperature, characterized by comprising the following steps: S1. a barrel pump is in communication with a first dispenser and a second dispenser respectively through a DMM preheater; the first dispenser and the second dispenser are both charged with trioxymethylene; the barrel pump alternately pumps preheated dimethoxymethane into the first dispenser or the second dispenser to form uniform mixture; and the uniform mixture is pumped into a material tank through a first feed pump; wherein the molar ratio of dimethoxymethane to trioxymethylene is (2 - 10):1; S2. a solid catalyst is added in a reactor, and the reaction materials in the material tank are pumped by a second feed pump into the reactor through a four-way channel valve; the two radially opposite ports of the four-way channel valve are respectively connected to the first separation membrane tube and the second separation membrane tube; and the other two radially opposite ports of the four-way channel valve are respectively connected to the inlet and the outlet of the reaction materials; the first separation membrane tube and the second separation membrane tube alternately feeds or discharges the reaction materials by the channel-switching action of the four-way channel valve; the reaction is carried out in the reactor with the catalyst and the reaction materials being uniformly mixed under a continuous and stable stirring condition; the weight space velocity is controlled at 0.3 to 50 h -1; the reaction temperature is 30 to 69°C; the reaction pressure is 0.5 to 2.0 MPa; S3. a gas flow control meter is configured on the upper part of the side wall of the reactor; the flow control meter detects and controls the input speed of nitrogen for matching the discharge rate with the feed rate of the reaction materials and controlling the distance between the liquid level of the reaction materials and the upper cap of the reactor to be 5 to 80 cm by adjusting the pressure in the reactor; the reaction materials are separated from the catalyst through the first separation film tube or the second separation film tube at the outlet of the reactor; the catalyst remains in the reactor, while the reaction materials are introduced into a product collection tank; S4. the mixture in the product collection tank is sent to a subsequent separation device for further separation into reaction product DMM 2-8 and unreacted materials; the unreacted materials are circulated to the material tank. S1. a barrel pump is in communication with a first dispenser and a second dispenser respectively through a DMM preheater; the first dispenser and the second dispenser are both charged with trioxymethylene; the barrel pump alternately pumps preheated dimethoxymethane into the first dispenser or the second dispenser to form uniform mixture; and the uniform mixture is pumped into a material tank through a first feed pump; wherein the molar ratio of dimethoxymethane to trioxymethylene is (2 - 10):1; S2. a solid catalyst is added in a reactor, and the reaction materials in the material tank are pumped by a second feed pump into the reactor through a four-way channel valve; the two radially opposite ports of the four-way channel valve are respectively connected to the first separation membrane tube and the second separation membrane tube; and the other two radially opposite ports of the four-way channel valve are respectively connected to the inlet and the outlet of the reaction materials; the first separation membrane tube and the second separation membrane tube alternately feeds or discharges the reaction materials by the channel-switching action of the four-way channel valve; the reaction is carried out in the reactor with the catalyst and the reaction materials being uniformly mixed under a continuous and stable stirring condition; the weight space velocity is controlled at 0.3 to 50 h -1; the reaction temperature is 30 to 69°C; the reaction pressure is 0.5 to 2.0 MPa; S3. a gas flow control meter is configured on the upper part of the side wall of the reactor; the flow control meter detects and controls the input speed of nitrogen for matching the discharge rate with the feed rate of the reaction materials and controlling the distance between the liquid level of the reaction materials and the upper cap of the reactor to be 5 to 80 cm by adjusting the pressure in the reactor; the reaction materials are separated from the catalyst through the first separation film tube or the second separation film tube at the outlet of the reactor; the catalyst remains in the reactor, while the reaction materials are introduced into a product collection tank; S4. the mixture in the product collection tank is sent to a subsequent separation device for further separation into reaction product DMM 2-8 and unreacted materials; the unreacted materials are circulated to the material tank.