The invention belongs to the technical field of the core fracture-forming method, and particularly relates to a core indoor artificial fracture-forming method for tight sandstone. The method comprisesthe following steps: selecting a tight sandstone plunger; fixing the core of the tight sandstone plunger by using a protective sleeve; opening a gap on the end face of the core; inserting a fracture-opening needle into the gap, pressurizing the fracture-opening needle to form the fracture; and after the fracture-forming, withdrawing the fracture-opening needle. The problem in the current fracture-forming method that the mechanical property of the core is seriously damaged or the structural integrity damage of the core is generated in the fracture-forming process is solved. The method is capable of guaranteeing the structural integrity of the fracture-forming core, and reserving the original mechanical property of the tight sandstone core in the greatest degree.