The invention discloses a split negative-pressure backflow machine and a technological method, and belongs to the technical field of acidification backflow and negative-pressure plug removal of oil-water wells. An upper joint is connected with a middle joint; the middle joint is connected with an outer cylinder and a shunt joint; an inner cavity of the middle joint is connected with diffusion pipes and a throat pipe; an inner cavity of the shunt joint is connected with a nozzle and a guide cone; the outer periphery of the shunt joint is connected with a backwashing valve and a lower joint; and a locking ring is connected between the middle joint and the diffusion pipes. The split negative-pressure backflow machine and the technological method have the advantages of split structure, enlargement of internal acid squeezing channel and improvement of acid squeezing efficiency. The device solves the problems of overhigh acid squeezing pressure and easy blockage of the throat pipe by a temporary blocking agent.