The invention relates to a composite technology for fixed length stretching. The technology comprises the following steps: coating an imaging coating on a basal membrane; arranging appearance seams on the basal membrane; installing a holographic transferring membrane between an uncoiling roller of the transferring membrane and a stretching and traction roller of the transferring membrane in a composite device of a fixed length stretcher; arranging a photoelectric sensor between the stretching and traction roller of the transferring membrane and a gluing system, calculating the actual length of prints between the appearance seams by a control circuit according to a signal of print seams detected by the photoelectric sensor and comparing the actual length of the prints and the length of prints in a memory; and outputting a control signal by the control circuit according to an obtained comparison result, controlling the traction force of the stretching and traction roller of the transferring membrane by the control signal and enabling the actual length of the prints to be equal to the length of the prints in the memory. The technology can control the size between plate seams on the basal membrane effectively, thereby enhancing the product quality and the tea production efficiency of transfer printing.