Disclosed is a tectonic coal block type briquette coal triaxial sample preparation device with controllable apparent. The sample preparation device comprises a concrete fixed groove with an opening inthe top; a molding box is arranged at the upper part in the concrete fixed groove; an upper positioning and plugging system is arranged between the top of the molding box and a fixed plate, and a cutting sampling system is arranged on the upper positioning and plugging system; a lower pressurizing system is arranged between the bottom of the molding box and the bottom of the concrete fixed groove; a left pressurizing system is arranged between the left side part of the molding box and the left side wall of the concrete fixed groove; and a front pressurizing system is arranged between the front side part of the molding box and the front side wall of the concrete fixed groove. The invention further discloses a sample preparation method of the tectonic coal block type briquette coal triaxialsample preparation device with controllable apparent. The triaxial pressing process provided by the invention better conforms to the stress state of the in-situ layer, and the stress distribution ofthe sample in the briquette coal pressing process is more uniform; the coal sample apparent density change can be monitored in the briquette coal pressing process, so that the pressing degree of different coal samples can be controlled; and damage of coal samples in the de-moulding process can be reduced to the maximum extent.