In order to quantitatively evaluate the fracturing effect of hydraulic fracturing by voltage pulse on coal rocks

and determine that whether the technology is suitable for the voltage and water pressure loading in engineering practice or not

the voltage pulse hydraulic fracturing ultrasonic testing test is designed

the fracturing effect of this technique on coal rocks under different loading conditions is quantitatively characterized by the numerical calculation from damage variables and crack propagation width

and its advantages compared to the operation of hydrostatic fracturing merely is evaluated. The conclusions are as follows: ①Due to the fluctuation of load fluid electrical pressure

the damage degree around the borehole is the most serious

reducing with the decreases of the fluctuating pressure. ②The damage variables and crack width are positively correlated with the loading voltage

which increase with the increase of voltage. ③The fracturing effect of hydraulic fracturing by voltage pulse on coal is quantitatively analyzed from damage variable and crack width

which can provide reference for coalbed methane.