The utility model provides a leak prevention device for a sleeve type expansion joint, which comprises a deslagging pipeline, a dust remover, a gas-solid separating device, an extraction pipeline, a pressure probe, a regulating valve and a dust remover, wherein the gas-solid separating device is arranged in the extraction opening of the expansion joint and used for separating bed material particles; the extraction pipeline is connected with the gas-solid separating device; the pressure probe is arranged on the outer sleeve of the expansion joint and used for monitoring the pressure state in the outer sleeve of the expansion joint; the regulating valve is arranged in the extraction pipeline and used for regulating the negative pressure state in the outer sleeve of the expansion joint; and the dust remover is arranged at the outlet of the extraction pipeline and used for absorbing bed material particles pumped into the extraction pipeline. Through the leak prevention device for the sleeve type expansion joint, the problem that an expansion joint extraction pipeline in the prior art is easy to block can be solved.