The gradual erasing operation from reset state to set state adjusting pulse amplitude, duration time and falling time respectively in phase change device using Ge1Cu2Te3 is investigated. For this procedure, a relatively high voltage and increased falling time, which was able to produce both long-term potential and long-term depression in the time interval between pre-spike and post-spike is choosing. The results suggested that the presence of synaptic behaviour was due to controlled falling time rather than pulse amplitude.