The invention relates to a device for stably and continuously preparing and releasing chlorine dioxide, a use method, and a preparation method of a chlorine dioxide precursor solid tablet. The device comprises a reactor and an air conveying device, wherein the reactor is a reaction tank of which the upper part is opened and the bottom is a waste storage groove; a support net is arranged in the middle of the reaction groove; a chlorine dioxide precursor solid tablet storage tank is arranged at the upper end of the support net; the chlorine dioxide precursor solid tablet storage tank is connected with the reaction tank through a first valve and a pipeline which inclines downwards; a second valve in airtight is arranged between the support net and a waste storage tank; the aperture of the support net is not greater than that of the chlorine dioxide precursor solid tablet; the air conveying device comprises an air pump, a water bath pot with an air inlet and an air outlet; the air inlet is formed below a water bath level to be set; the air outlet is formed in the top of the water bath pot; the air inlet is communicated with the air pump through an air sample inlet tube; the air outlet is communicated with the reaction tank through a wet air sample inlet tube; the connecting part of the air outlet and the reaction is arranged between a second support net and the second valve.