Abstract: Discretization method is usually important in intelligentmodeling or controling for welding process.The evaluation criterion for discretiztion methods inwelding field were discussed.Based on the selected evaluation criterion, common discretization methods were compared, where a welding data set was obtain in pulsed GTAW experiment as modeling data and rough set modeling method was used to obtained a model that can predict backside width of melten pool.It showed that discretizationmethod based entropy performes better.Based on the entropy algorithm, a modified discretization algorithm was put forward, and the last result showed that this method was better and suited for the welding field.