The Target Alignment Sensor (TAS) was an important component of the Inertial Confinement nuclear Fusion (ICF) range, and its position in the target chamber was one of the main factors to ensure the accuracy of target positioning. In order to realize micro-level adjustment and positioning accuracy, it was necessary to use an appropriate mechanism to adjust the target alignment sensor. A method combining theoretical analysis, finite element simulation and experimental verification was adopted to study the deformation and stability of the y-adjusting mechanism. According to the stress deformation analysis of the y-adjusting mechanism, the theoretical relation of the structural stress deformation was obtained, and the stiffness and stability of the y-adjusting mechanism could be theoretically optimized. Deformation and stability analyses were conducted for the y-adjustment mechanism under certain constraints based on the finite element simulation. The experimental device was used to test the static stability of the target alignment sensor. The experimental results show that the y-deformation of the target alignment sensor is reduced from the original 7.9 μm to less than 2 μm, and the dynamic stability satisfies the stability requirement of 2 μm/2 h. The experimental results depicted the same trend as the theoretical and finite element deformation analyses, which demonstrates the correctness of the theoretical and simulation analyses.