The invention relates to a low-grade powder coal continuous retort technique and device. The technique comprises the following steps: low-grade powder coal enters an external-heating continuous retort furnace through a double-seal charging device and a material cache bin, and raw gas is collected through a gas collector and a gas collection cavity and led out by a gas collection system; and the furnace material subjected to retort is discharged through a discharge device, wherein the discharge device has two optional forms, the discharge device 1 discharges the powdery furnace material through a coke discharge roller, and the discharge device 2 performs primary cooling on the furnace material, continuously and uniformly discharges the furnace material into the furnace material cache device through a discharge control valve, performs secondary cooling and discharges the furnace material via a quantitative discharge valve. The technique implements the continuous retort process in the external-heating continuous retort furnace by using the low-grade powder coal as the raw material, and can prevent the air inside and outside the retort chamber from leakage, thereby implementing effective sealing. The raw gas generated in the retort process can be quickly led out, and the light oil yield and gas caloricity can be enhanced. The powdered coke can be controlled to be discharged uniformly and continuously in the coke discharge process, and the semicoke quality is controllable and adjustable.