The invention provides a water-soluble polymer solution degrading agent, which is prepared from the following components by mass percent: 1 to 5 percent of ferrous compound, 1 to 10 percent of ascorbic acid, and the balance of water. According to the water-soluble polymer solution degrading agent provided by the invention, the ascorbic acid and the ferrous ions are utilized to coordinate to prepare a ferrous solution with long-time stability, so that favorable stability is realized; the ferrous solution is added into a water-soluble polymer solution so as to activate molecular oxygen to form a free radical so as to degrade a polymer, and the water-soluble polymer solution degrading agent can be applied in an oil field fracturing fluid gel breaker and a polymer-containing oil field produced liquid water treatment agent. After degradation, the apparent viscosity of the solution is less than or equal to 5.0mPa.s, and the recycle effect and the efficiency of produced sewage are improved.