The utility model relates to an expansion clog prevention packer. The utility model is characterized in that the inner part of a hollow cavity at the lower end of an upper contact is arranged in turn with a valve and a spring, wherein, the valve is used for sealing the upper contact and a center pipe through a rubber ring and an O-shaped ring. The center pipe and the inner part of the hollow cavity at the lower part of a rubber cylinder seat are provided with a lower center pipe, an adjusting ring is fixed on the lower center pipe through pins and an internal thread is fixed with a liquid cylinder with a circular bead, the inner part of the hollow cavity formed by the lower center pipe and the liquid cylinder is provided with a lower contact, and the problems of complex technology and high cost for the original clog prevention are solved. The utility model has the advantages of simple structure, simple clog prevention process and low cost.