Abstract: A device for determining an expansion pressure and an expansion displacement generated by coking coal based on self-regulation of a spring includes a pyrolysis reactor, which is provided in a high temperature carbonization furnace. Two porous pressing plates are provided at both sides of a coal sample, and two metal filter plates are provided at both sides of the sample. Upper and lower openings of the reactor are sealed respectively with a connecting flange. The pressing plate above the sample is connected to a mounting baffle of a detection mechanism through a lightweight connecting rod and a spring. The detection mechanism is provided with a displacement sensor and a pressure sensor. This application further provides a detection method using the above device.