The invention discloses a preparation method of an individualized 3D printed high tibial osteotomy guide plate, for an osteotomy guide plate of a 3D printed high tibial osteotomy. Before a surgery, according to the CT data of the knee joint of a patient, through computer simulation modeling and a 3D reconstruction procedure, the deformity shape of the tibia shape of a patient is printed in proportion being 1 to 1, an osteotomy position is designed before the surgery through a 3D printing technique, and finally an osteotomy guider which is completely fitted to the near end of the tibia of the patient is designed through a model material; and in the surgery process, the osteotomy guider is directly fitted to the near end of the tibia in the surgery process, according to the preoperative osteotomy scheme, osteotomy surgery operations are immediately started, under regulation for guaranteeing accuracy, the surgery operation steps are simplified, the anaesthesia time of the surgery is shortened, the safety of the surgery of the patient is guaranteed, and the preparation method has great clinical promotion effects. A steel plate can be fixed according to tibia near ends provided by different factories, the position and the direction of the osteotomy of the tibia can be in individualized design, and the preparation method has definite diversified flexibility.