The invention discloses a testing device simulating a bioretention pond comprehensive efficiency under nature rainfall conditions; the testing device comprises a test bed and a test barrel placement zone; the test bed is a dual-bed surface structure, and comprises a water seepage plate and a water collecting plate, wherein the water collecting plate is arranged below the water seepage plate; the water seepage plate surface is provided with a plurality of water seepage holes; the water seepage plate periphery is provided with an outer stop plate so as to form a conflux space; a movable separation assembly is arranged in the conflux space so as to separate the conflux space into a water gathering area and a water discharge area; the outer stop plate side opposite to the water gathering area is provided with a plurality of conflux discharge ports; one side of the conflux discharge ports is the test barrel placement zone; an anthropogenic rainfall assembly is arranged above the test barrel placement zone and the water seepage plate. The testing device simulating the bioretention pond comprehensive efficiency under nature rainfall conditions can carry out quantitative analysis, thus providing basis for making a sponge city construction scheme; the testing device is low in making cost, easy to mount/dismount, strong in operationality, and wide in application aspects.