In order to study the influence of different decoupling coefficients of water-coupled charge on blasting effect,a transparent and uniform cylindrical PMMA material with 250 mm in diameter and 200 mm in height was used as the test specimen.Meanwhile,a DDNP explosive was used to apply blasting load.In the test,the explosive quantity was fixed at 40 mg.At the same time,a water-coupled charge structure was used,and the decoupling coefficient was changed with different hole diameter and charge diameter.By comparing the number and distribution of internal cracks of the specimen and the size of crushing area,the effects of three different decoupling coefficients(1.4,2.0,2.67) on blasting effect were analyzed.It is found that appropriately increasing the decoupling coefficient of water-coupled charge can increase the number of cracks,make the crack distribution more uniform,increase the fracture area and reduce the diameter of the broken zone.Besides,there is an optimal decoupling coefficient to achieve the best blasting effect.Among the three uncoupling coefficients,the optimal decoupling coefficient is 2.67.In the test,the transparent and uniform characteristic of PMMA material are used to observe the blasting fracture behavior intuitively.The test results are very reliable and generally applicable to brittle materials.