The utility model discloses a brine two-stage purification continuous reaction device, which comprises a pump and a water ejector in turn, wherein the water ejector comprises a liquid inlet pipe, an air inlet pipe, an inspiration chamber, a mixing pipe, a diffusion pipe and a tail pipe; a nozzle is arranged at the tail end of the liquid inlet pipe; the tail end of the air inlet pipe is communicated with the inspiration chamber; the inspiration chamber, the mixing pipe, the diffusion pipe and the tail pipe are connected and communicated in turn; a liquid outlet is formed at the tail end of the tail pipe; and the pump is connected with the liquid inlet pipe. The brine two-stage purification continuous reaction device disclosed by the utility model is good in mixing performance; the calcium ion removal rate can be up to 60%; the pH value of reaction liquid is steady and lower in fluctuation; flue gas can be sufficiently utilized, so that the brine two-stage purification continuous reaction device is energy-saving and environment-friendly; dispersing and absorbing reactions of gases can be realized without external mechanical force, so that the energy consumption is saved; the structure of equipment is simple; low-level installation can be realized; and the brine two-stage purification continuous reaction device is convenient and rapid to operate, replace and maintain.