The utility model discloses a waste gas purification device of a diesel internal combustion engine, which comprises a casing, a gas inlet pipe, a gas cross leakage pipe and an exhaust pipe. A cavity separating plate and a pipe type air cooling roll booster are disposed in the casing. The top of the cavity separating plate is fixedly connected to the top of the casing, the upper portion of the cavity separating plate is provided with gas cross leakage holes, and the lower end of the cavity separating plate is provided with a liquid cross leakage hole. The cavity separating plate divides the inside of the casing into a distillation chamber, a cooling chamber and a purification chamber. Chemical solution is filled in the lower portion of the casing, and a filter is disposed on liquid surface. The gas inlet pipe is communicated with the filter at the lower portion of the distillation chamber. The upper end and the lower end of the gas cross leakage pipe are respectively communicated with the gas cross leakage hole and the filter. The lower ends of the gas inlet pipe and the gas cross leakage pipe are respectively provided with a gas mitigating hole. The casing is provided with a liquid adding pipe, and a liquid adding hole is disposed at the upper end of the liquid adding pipe. An exhaust chamber which is communicated with the exhaust pipe is arranged inside the purification chamber, a separating plate and a gas screen are arranged in the exhaust chamber, and the gas cross leakage holes are disposed at the lower end of the separating plate and at the upper portion of one end of the exhaust chamber, and a filter liquid hole is arranged at the lower portion of the end of the exhaust chamber. The waste gas purification device of the diesel internal combustion engine resolves the technical problem that the prior art cannot effectively purify waste gas of the diesel internal combustion engine.