The invention relates to a rubber-ring sealed by-pass pressure-balance sleeve compensator which comprises an outer sleeve, a core pipe connecting pipe A, a core pipe connecting pipe B, a reducing connecting pipe, rubber ring seal components, elliptical convex blind plates and a breathing pipe, wherein the core pipe connecting pipe A and the core pipe connecting pipe B are provided with flow guiding holes; a ring-shaped seal cavity is formed between the outer sleeve and an inner pipeline through one rubber ring seal component; a seal cavity is formed between the reducing connecting pipe and the elliptical convex blind plates on two sides through the other rubber ring seal component; the core pipe connecting pipe A can slide along the two rubber ring seal components to compress the inner seal cavity to realize compensation for deformation of the pipeline. Compared with the prior art, the rubber-ring sealed by-pass pressure-balance sleeve compensator has the beneficial effects that 1) the sealing is reliable and long-lasting, and no maintenance is needed in an operational process; 2) no internal pressure pushing force is transmitted to the outside, the force of friction is small, the stress requirement of a fixing bracket is can be greatly reduced, and the construction cost and material cost of the fixing bracket are lowered; 3) the mounting is convenient since the compensator is mounted only by welding joints at two ends and the pipeline to be connected.