The invention discloses a method for correcting a span during rock blasting damage cross-hole sound wave test. The method is suitable for span correction between an emitting transducer and a receiving transducer in a sound wave hole for rock blasting digging damage sound wave monitoring in blasting digging engineering. A sample is measured through a sound wave hole before blasting to obtain coordinates A (xa, ya, za) and B (xb, yb, zb) of orifices A and B; after blasting, the orifices of the dug residual sound wave hole are cleared, and the sample is measured to obtain the coordinates A' (x'a, y'a, z'a) and B' (x'b, y'b, z'b) of the two orifices A and B; an actual distance between the emitting transducer and the receiving transducer at the moment can be precisely calculated through a formula, wherein eta=xb+(xb-x'b)tbi-xa-(xa-x'a)tai, delta=yb+(yb-y'b)tbi-ya-(ya-y'a)tai, phi=zb+(zb-z'b)tbi-za-(za-z'a)tai. According to the method, the span can be corrected only through the coordinates of the orifices of the conventional sound wave monitoring hole of the engineering before and after blasting without measuring an inclination angle and an inclination direction of the sound wave detection hole; extra workload and extra equipment are not added; the method is easy to operate, precise and reliable. The calculating formula of the span correction method provided by the invention is simple; calculation is easy, and sound wave test analysis software is easily programmed and implanted.