Thermomechanical analyses in laser-spot-welding (LSW) technique for a dual-in-line (DIP) type package has been studied experimentally and numerically to predict post-weld-shift (PWS). Experimental results show that the PWS of optoelectronic component changes sensitively depending on process parameters such as laser energy, beam delivery position, weld joint design and so on. This indicates that the PWS in laser packaging can be minimized by properly controlling the process parameters. A finite element method (FEM) has been carried out on the analysis of the effect of laser parameters and geometry of joint variation on PWS in laser packaging. And experimental studies of laser spot welding and electronic speckle pattern interferometry (ESPI) have also been conducted to validate the numerical model. A satisfactory agreement between the experimental results and FEM calculations suggests that the FEM provides one of the effective methods for predicting the PWS and optimizing package design in LSW technique for optoelectronic packaging. By using the numerical method above this work has led to an understanding of the effect of laser energy variation and joint design on thermal distortion. Hence the PWS can be controlled to produce a reliable laser module with high yield and high performance.