The invention discloses a plate structure impact monitoring method based on the fractal theory, and belongs to the technical field of impact monitoring of structure health monitoring. The method comprises steps as follows: step one, distribution of distributed fiber bragg grating sensors; step two, computation of box-counting fractal dimensions of the fiber bragg grating sensor impact response signals; step three, collection of the fiber bragg grating sensor impact response signals corresponding to sample impact points and box-counting fractal dimension computation; step four, collection of the fiber bragg grating sensor impact response signals corresponding to to-be-detected impact points and box-counting fractal dimension computation; step five, computation of x-axis coordinates of the to-be-detected impact points; step six, computation of y-axis coordinates of the to-be-detected impact points. According to a positioning algorithm, the positions of the impact points are judged through computation of the box-counting fractal dimensions of fiber bragg grating sensor impact response signal frequency spectrums, and the method has the characteristics of no need of a large number of prior knowledge, simplicity, rapidness, convenience, high practicability and the like.