The invention discloses a double-loop test monitoring assembly and a double-loop test device and method. The double-loop test monitoring assembly is arranged on a double-loop assembly, and comprises awater level balance and data transmission assembly, and a horizontal adjustment assembly used for fixing the water level balance and data transmission assembly on the double-loop assembly; the waterlevel balance and data transmission assembly comprises a water injection assembly, a flow meter and a main controller, wherein the water injection assembly is used for injecting water into an inner loop of the double-loop assembly and the position between the inner loop and an outer loop; and the flow meter is used for recording the water injection flow of the water injection assembly and the corresponding moment of the water injection flow, the main controller is used for acquiring the diameter of the inner loop and calculating a permeability coefficient according to the diameter of the innerloop, the water injection flow and the corresponding moment thereof. According to the assembly, the double-loop test efficiency and accuracy can be effectively improved, and the real-time monitoringof a double-loop test is realized.