The invention discloses a mirabegron sustained release tablet as well as a preparation method and a quality detection method thereof, and belongs to the technical field of medicines. The mirabegron sustained release tablet is prepared from the following raw materials and auxiliary materials in percentage by weight: 5 to 35 percent of mirabegron, 10 to 40 percent of polyoxyethylene, 0.6 to 6.0 percent of hydroxypropyl cellulose, 0.08 to 0.20 percent of butylated hydroxytoluene, 0.6 to 1.5 percent of magnesium stearate and the balance of polyethylene glycol. Wet granulation is adopted, the tablet fluidity is good, the quality is stable and uniform, the technological operation is simple, and the method is suitable for industrial production. According to the prepared mirabegron sustained release tablet, the formula content of mirabegron accounts for 15-25%, the long-time stable effective drug blood concentration can be maintained, the proportion of the antioxidant is low, the requirements of laws and regulations are met, and the medication safety is guaranteed. The product disclosed by the invention is combined with Shenkangning capsules and pumpkin seed pollen compound protein solid beverage to achieve a relatively good curative effect on patients with overactive bladder and patients with kidney-yang deficiency accompanied with symptoms such as nocturia increase, urinary incontinence, frequent urination and urgent urination.