The invention discloses a deep foundation pit supporting method for controlling deformation of a deep foundation pit in a double-support supporting and protecting system. The deep foundation pit supporting method comprises the steps of excavating soil at the middle parts of double-support parts, corresponding to the double-support supporting and protecting system, in the deep foundation pit; constructing first support beams at the middle parts of the double-support parts; excavating soil at the two ends of the double-support parts, corresponding to the double-support supporting and protecting system, in the deep foundation pit; constructing second support beams at the two ends of the double-support parts, so as to ensure that the second support beams are combined with the first support beams to seal the deep foundation pit at the double-support parts; excavating soil at non-double-support parts, corresponding to the double-support supporting and protecting system, in the deep foundation pit; and constructing non-double-support part support beams at the non-double-support parts, so as to seal the entire deep foundation pit. According to the deep foundation pit supporting method, the soil at the double-support parts is firstly excavated, construction is carried out from the middle part to the two ends, after the first support beams in the middle of the double-support parts are retracted, the parts at the two ends of the double-support parts are quickly sealed through utilizing the second support beams, supports at the double-support parts are sealed, the time when the foundation pit is not supported is shortened, and the foundation pit deformation is controlled.