The model is established that fracturing fluid leakoff in coal bed with/without the reopened natural fractures, and its analytical solution is present.

• 建立了天然裂缝开启前、后的煤层压裂液滤失数学模型,给出了模型的解析解,并进行了计算分析,对于煤层压裂设计分析具有一定的实用意义。