Transient electroluminescent measurement system is used to study the inside charge behavior of prepared organic light-emitting diodes (OLEDs) in this article. Two rectangular pulses with a fixed time interval are supplied on the device. We can analyze the inside charge storage and the emitting process by measuring the transient EL and transient current of the device. OLEDs based on the m-MTDATA∶3TPYMB (1∶1) system was prepared. We found that the stable EL intensity increase when the second pulse is supplied. And the increment reduced with the increased current. We also find the electroluminescent under the second pulse decayed faster than that of the first pulse. This is because of the quenching due to the polaron-exciton effect (TPQ) is more serious in the emitting layer under the second pulse.