The invention discloses a visual-
model testing apparatus and testing method for seepage-stress-coupled internal 
piping penetration. The testing apparatus is composed of four parts, i.e., a variable-head control and 
liquid circulation system, a vertical loading and penetration 
system, a 
laser control system and an 
image acquisition system and can carry out experimental study on internal 
piping penetration of non-steady seepage under the conditions of different stresses, different contents of fines, different grading and the like and research on the characteristics of 
particle loss and deformation and fracture in the process of seepage. The invention also provides a 
visual testing method for seepage-stress-coupled simulated 
erosion-type internal 
piping. According to the method, head difference is applied to a piping soil sample in a 
stress field in the vertical loading and penetration system in virtue of the variable-head control and 
liquid circulation system, so a seepage-
erosion-stress three-field coupled internal piping test is realized. The visual-
model testing apparatus and testing method provided by the invention are simple in procedure, easy in fabrication, capable of realizing direct and in-depth observation, economic and good in 
operability, so the meso-scopic mechanism of seepage-stress-coupled internal piping is revealed preliminarily, and a testing foundation is provided for subsequent research.