Abstract: The lowermeter gate of No.2 shiplock,set up at Gezhouba Project is the largest one in China and up now it is one of the largest gates in the world,too.Each gate,manufactured in factory and made up of 10 sections for transporting is about 600 ton in weight and 34.05 m.in height and sustains a load of 9850 ton of hydrostatic pressure inwork.The welding process of the gate performed at field is to put the sections of the gateo ne upon another in vertical position.This thesis discusses what method of welding we selected,what measures we toke for controlling over deformations and all in all,how we have fulfilled our work by integrating theoretical calculation of deformations,analysis of model tests and welding sequences with practice.