Abstract: Self-correlation analysis is an important analyzing method in signal analysis and processing.Some welding parameters attribute values, such as current, voltage etc, were acquisited in GMAW (gas metal arc welding)process.The stability of droplet transfer process in GMAW and welding parameter were studied.Using time domain self-correlation character principle in digital signal analysis and processing, periodic property of welding current and voltage were identified.Through the acquired signal time domain periodic property, the stability of droplet transfer process in GMAW can be visually reflected