Crack expanding monitoring method for hydrofracturing ore rock pretreatment test

The invention relates to a crack expanding monitoring method for a hydrofracturing ore rock pretreatment test. The crack expanding monitoring method comprises the following steps that firstly, a geology drilling machine is used for punching a fracturing drill hole and six to eight observation drill holes; secondly, a signal exciter, a water level monitoring meter and a slight shock detector are sequentially arranged in each observation drill hole from bottom to top; thirdly, testing and data collecting are conducted; and fourthly, the longitudinal wave speed of a test area rock mass before andafter fracturing is compared to evaluate the fracturing effect, inversion of slight shock signal data in the slight shock detectors is conducted for conducting focus positioning, and the hydraulic crack expanding position is determined. The crack expanding monitoring method has the advantages that firstly, the crack expanding range is visually and effectively determined; secondly, interference ona monitoring system from