Abstract: The nonlinearity in GMAW process determines its chaotic characteristics.Correlation dimension is a major quantitative analysis index in chaos researching of dynamical system.In this paper phase space reconstruction was used to analyse the current signal time sequence in GMAW by calculating correlation dimension.By changing welding voltage,welding current and gas flow rate,the chaotic characteristic of arc welding under different parameters was discussed.Studies show that chaos in GMAW welding process exists not only in short circuit transition,but also in droplet transition.On this basis,further study of the variation of correlation dimension under different parameters was put forward.Correlation dimension can be used as the basis for evaluating welding process stability.It means the smaller the correlation dimension is,the welding process is more stable and welding parameters are more appropriate.The criterion provides theoretical basis for the identification of chaos,which can be used in process optimization experiments for welding parameters selection and monitoring the stability of the welding process.