The gravitational wave telescope, a critical payload of space-based gravitational wave detection satellites, experiences significant optical path stability issues due to deformations in its support structure. These deformations are primarily caused by thermal gradients and involve multiple degrees of freedom, underscoring the importance of studying methods to measure multi-degree-of-freedom deformations of the telescope frame. However, in the measurement process, the coupling of multiple degrees of freedom can adversely affect measurement accuracy, necessitating thorough decoupling analysis. Here, we introduce a preliminary technology for multi-DOF deformation measurements through decoupling analysis and noise evaluation of the single-arm measurement optical path. The measurement system meets the requirement of having background noise less than 10 pm/Hz1/2 near 1 Hz and 2 nm/Hz1/2 near 1 mHz. This analysis could help a structural deformation measurement framework to establish and provide broader insight into the response of methodological system for telescopes.