Abstract: In order to prove the cracking effect of high-pressure pulse discharge technology on coal bodies with different physical and mechanical properties, similar materials are used to replace coal rock formations, and the high-voltage pulse discharge system is used to perform underwater discharge cracking test on similar materials with different strengths and the experimental results is analyzed.The results show that from a macro perspective, the greater the strength of the sample is, the greater the number of pulse discharges required to form a through crack, and the greater the energy requires.The smaller the strength of the sample is, the more abundant the cracks in the drill hole are.There are three stages of crack growth:the preparation stage, the development stage and the ring-breaking stage.However, with the increase of sample strength, the number of preparation stages increases, which requires more energy to prepare for the development stage.The crack growth speeds show a “slow-fast-slow” trend.From a microscopic point of view, the cracks around the drill hole widen significantly with the increase of the number of experiments until they break, and this phenomenon becomes less obvious with the distance from the drill hole.