The invention provides a sealing testing device which comprises a frame, a positioning mechanism, a plugging mechanism, a plugging and clamping mechanism, a first air inlet testing mechanism, a secondair inlet testing mechanism, a marking mechanism and a dust removal mechanism. The positioning mechanism is arranged on the frame. The plugging mechanism, the plugging and clamping mechanism, the first air inlet testing mechanism, the second air inlet testing mechanism and the marking mechanism are arranged on the periphery of the positioning mechanism. The dust removal mechanism is arranged at the marking mechanism. The plugging mechanism is perpendicular to the plugging and clamping mechanism. A to-be-tested product, namely a turbocharger, is positioned by the positioning mechanism, one side of the product is plugged by the plugging mechanism, and the other side of the product is plugged and clamped by the plugging and clamping mechanism. Therefore, the product is completely positioned,a first air inlet of the product is tested by the first air inlet testing mechanism, another air inlet of the product is tested by the second air inlet testing mechanism, and after the testing is finished, the product is marked by the marking mechanism, and then the product is blown for dust removal by the dust removal mechanism, so that the turbocharger is subjected to positioning, air inlet testing, marking and dust removal automatically, the testing is convenient and efficient, the testing precision is high, and labor is saved.