In order to study the influence of weak interlayer parallel to the blast hole on rock blasting crack propagation,blasting simulation experiments was carried out by pouring cement mortar test blocks with 40 cm×40 cm×36 cm in length,width and height and different weak interlayers(soil and stone,soil,water) into steel mold.Six radial strain bricks with a depth of 10 cm were symmetrically embedded along the vertical direction of the weak interlayer and 8 cm,12 cm and 18 cm away from the blast hole in the pouring process of the test block,which were used to monitor the internal strain changes in the blasting process of the test blocks by using ultrahigh dynamic strainometer; At the same time,the blasting crack propagation process of the test blocks was observed by high speed camera.The crack propagation results and strain differences between the two sides of the same test block(the weak interlayer side and the intact side) and the weak interlayer side between different test blocks were compared and analyzed.The results show that:In the same test block,the blast hole crack growth rate near the weak interlayer side is faster than the complete side.Between different test blocks,as the strength of the weak interlayer decreases,the crack propagation speed of the blast hole near the side of the weak interlayer is faster,and the crack propagation is more adequate.The weak interlayer has the effect of preventing crack propagation,and the lower the strength of the weak interlayer is,the more obvious the crack arrest effect becomes.Wing cracks are generated at both ends of the weak interlayer,and the lower the strength of the weak interlayer,the faster the propagation speed of the wing cracks.The peak strain value of each measuring point of the test block is between 0.0178~0.0640,and the corresponding peak stress is 49.9~179.2 MPa.As the distance increases,the attenuation speed of the stress wave in a certain range shows a large to small,and then small to large trend.The lower the strength of the weak interlayer is,the faster the explosive stress wave attenuates.