The invention discloses a purification method of refined arsenic trioxide. The purification method is characterized by including the steps that a coarse arsenic trioxide material is crushed to be withthe particle size of 3 cm or less, and fed into a drying section of a rotary kiln through a screw feeder and other devices to be subjected to heating and water evaporating; the material is then fed into a distillation section of the rotary kiln, and the kiln temperature is controlled at 500-550 DEG C; and gas formed by distillation enters a bag filter, an intercooler, a bag collector, a sink, a defogging chamber and a fan in order, refined arsenic trioxide products are collected through the intercooler and the bag collector, the rest of smoke enters the sink and the defogging chamber for treatment and recycling, and recycled smoke then enters the distillation section of the rotary kiln for circulating gasification to prepare products. The whole purification and preparation technical method of the arsenic trioxide is closed and flue gas exhaust circulation, in the way, the standard arsenic trioxide products with the brand being As2O3-1 can be prepared with the characteristics of high efficiency, environmental protection and energy saving.