Laser butt welding of guide sheath of pressurized water reactor control rod guide tube（CRGT） is studied. The laser welding heat source,laser welds shrinkage of guide sheath and laser welding deformation are modeled and analyzed. The simulation technology of laser welding deformation of guide sheath is established,which provides theoretical guidance for the manufacture of laser welding of CRGT,including laser welding test and thermal cycle test,macroscopic appearance of weld,residual stress test,heat source model establishment and parameter determination,laser weld shrinkage model and welding deformation prediction. Finally,the stable laser welding parameters are obtained,should be tested using a φ10.26 mm drop bar gauge can go though the CRGT freely in four positions of 0°,90°,180°,270° with the speed of 4～5 m/min,and the friction force is less than 9.07 kg.