The invention discloses a device for improving the enclosure net culture base substrate environment, and aims at providing a device capable of effectively relieving the culture field sea area substrate environment eutrophia, reducing the influence of the aquiculture on sea substrate environment and improving the enclosure net culture base substrate environment. The device comprises a base, an EM bacterium installing device, a triggering unlocking type locking mechanism and a floating triggering mechanism, wherein the EM bacterium installing device comprises a vertical installing tube positioned above the base, a buoyancy block arranged on the outer side surface of the vertical installing tube, an installing flat plate arranged in the vertical installing tube, and a plurality of EM bacterium storage devices positioned under the installing flat plate. Each EM bacterium storage device comprises an EM bacterium storage tank, a sealing and plugging post and a position limiting sleeve; the EM bacterium storage tank is provided with an opening in the lower end; the sealing and plugging post is arranged on the upper surface of the base and is used for sealing and plugging the lower end opening of the EM bacterium storage tank; the position limiting sleeve is arranged on the lower surface of the flat plate and is used for limiting the position of the EM bacterium storage tank; the triggering unlocking type locking mechanism is used for connecting the vertical installing tube and the base; the floating triggering mechanism is used for controlling the triggering unlocking type locking mechanism to unlock.