In laser process and laser scientific experiments it is an important research method to investigate analogy of physical parameters between the scale down models and the prototype structure by reduced-scale experiments. To the problem of the thermal-mechanical effects of the thin-walled pressure vessel irradiated by continuous wave (CW) laser, a series of approximatively geometrically scaling models with different scale-ratios are established in this paper. Laser flux and ratios of r(radius of laser spot) to R(radius of shells) keep the same for each scaling model. The similarity regularities of thermal-mechanical effects are analyzed and discussed by means of FEM numerical simulation method. The calculation results can give a guide to design for the scale down models and select for laser parameters in reduced-scale experiments.