The invention discloses a testing device and method for simulating the flowback performance of well soaking of a fracturing well. The testing device includes a 
fracturing fluid tank, a flowback 
fracturing fluid tank, a 
hydraulic fracturing pump, a flowback fluid collection 
beaker and a well soaking flowback testing 
system, the well soaking flowback testing 
system includes a box body, and an 
acoustic wave testing device, a 
temperature control device, a fracturing string and a square rock block which are arranged in the box body, a tress loading plate and a hydraulic block are arranged successively between the four surfaces of the square rock block and the inner wall of the box body, the 
acoustic wave testing device includes an 
acoustic wave transmitting probe and an acoustic wave receivingprobe, and hydraulic grooves are formed in the four outer surfaces of the box body. According to the testing device and method for simulating the flowback performance of well soaking of the fracturingwell, the situation and temperature of original 
crustal stress are considered, 
simulation of the rule of well soaking and flowback can be closer to the real situation, the flowback performance of shale under the 
complex joint net situation during volume transformation is further considered, and through a passive acoustic 
monitoring system, the flowback performance of 
fracturing fluid under different joint net complexity can be evaluated.