Abstract: In order to study the effect of technical parameters on the performance of high density polyethylene (HDPE) plastic welding pieces,with laser permeating a weld HDPE workpiece,mechanical tensile test was carried out and the morphology of the joint fracture was observed with a scanning electron microscopy. Results show that the joint intensity and elongation property accrete with smaller light spot and welding velocity and larger laser power. The welding joint is good and mechanical property is best with laser spot diameter in 2mm,laser power at 75W and welding velocity at 2mm/s. It is proved that laser welding HDPE is a feasible.