The invention discloses a simulation test method for geochemical effects of CO2 injection and forced mining of coal-bed gas, belonging to the field of mining of coal-bed gas; a pressurizing system (1) and a temperature-increasing system (3) provide pressure and temperature for a high-pressure test container (2); a high-temperature, high-pressure and sealed environment of a deep coal bed is simulated in the high-pressure test container (2); the whole test process is monitored through an electrical controlling and monitoring system; collection of a test sample in and after the test is completed through a liquid sample collecting system (5) and a gas sample collecting system (6). The simulation test method disclosed by the invention comprises the specific steps of tinning the sample, inspecting the air tightness, carrying out a geochemical reaction test on a coal rock, collecting a liquid sample in the test, collecting a gas sample in the test and cleaning a test system. By means of the simulation test method disclosed by the invention, the simulation test of geochemical reaction of a supercritical CO2/H2O system and a coal rock sample under a deep coal bed condition can be realized in a laboratory; and the simulation test method disclosed by the invention is high in temperature control precision, small in temperature fluctuation, safe and reliable.