The utility model provides a pipe external packer capable of being self-expandable when encountering water or oil. The pipe external packer capable of being self-expandable when encountering the water or the oil comprises a center pipe, rubber tubes and block rings, wherein the rubber tubes and the block rings are sleeved on the center pipe. A plurality of the rubber tubes are spaced by the block rings and fixed on the outer wall of the center pipe by an upper block cap and lower block cap. The rubber tubes are capable of being self-expandable when encountering the water or the oil. When in well-completion practice, the pipe external packer capable of being self-expandable when encountering the water or the oil is connected with a bushing in series through inner threads of an upper connector and outer threads of a lower connector, and down into a well together to a designated spot, liquid soaks rubber capable of expanding when encountering water and rubber capable of expanding when encountering oil, after a period of time, the rubber capable of expanding when encountering the water absorbs the water and automatically expands, rubber capable of expanding when encountering the oil absorbs the oil and automatically expands, and a purpose of sealing a borehole is achieved. The pipe external packer capable of being self-expandable when encountering the water or the oil has the advantages of being capable of effectively controlling water in a subsection mode, prolonging service life of an oil well, controlling production in the subsection mode, being high in expansion rate, and being capable of effectively sealing, simple in structure, convenient to construct, and high in reliability.