The invention discloses a novel cable-free type data bidirectional transmission device for a water injection well, capable of realizing a function of bidirectional transmission of data, including a flow and a pressure, from a well mouth of the water injection well to an underground injection layer and from the underground injection layer to the well mouth and adopting time sequence waves for coding. The device comprises an upper joint, an outer protective pipe, a pressure control short section, a water nozzle short section, a circuit control short section, a middle joint and a lower joint; theupper joint and the lower joint are connected with the outer protective pipe through threads; the outer protective pipe is internally provided with the pressure control short section, the water nozzle short section and the circuit control short section; the circuit control short section is internally provided with a flow sensor, a pressure sensor, a battery assembly and a logic control operationcircuit; and injected water enters the stratum after passing through a rapid opening/closing valve and the water nozzle short section. Time sequence pressure waves are decided by signal coding, a decimal system is adopted, timing is started when a signal is changed to a low level, and the signal represents a number N if becoming into a high level after N time units. For the novel cable-free type data bidirectional transmission device for the water injection well, on one aspect, data non-contact bidirectional transmission is realized; and on the other hand, coding is performed by adopting a form of the time sequence waves, and by combining with a design mode of the rapid opening/closing valve, the coding, decoding and transmitting efficiencies of the pressure waves can be greatly improved.