The invention relates to a high-fracture-toughness chalcogenide glass preparation method. A special thermal treatment step is arranged between a thermal insulation step and an annealing step of a batch mixture of chalcogenide glass. The thermal treatment step comprises the steps of cooling glass melt obtained after thermal insulation to 680 to 720 DEG C, standing for 1 to 2h, then putting into an ice and water mixture for 5 to 15s, then putting into 400 to 450 DEG C instantly to keep in constant temperature for 0.5 to 1h and quenching in air for 0.5 to 1min. The chalcogenide glass prepared by the preparation method disclosed by the invention has higher fracture resistance and better machinability and further keeps very good infrared permeability.