Accurately perceiving the multidimensional geometric information of complex equipment is crucial for improving product quality and production efficiency. We propose a multichannel time-domain wavelength division multiplexing frequency modulated continuous wave (FMCW) LiDAR integrated with the optical switch system scheme. This enables the implementation of time-domain wavelength division multiplexing technology for FMCW lasers, achieving the unified transmission of multi-length information through a single optical fiber channel. This system scheme enables parallel measurement of multiple targets and enhances the measurement accuracy of single targets by measuring the mean through multichannels, featuring versatility. In experiment, we achieved an overall absolute distance measurement accuracy better than 14 µm and individual channel accuracy better than 20 µm for non-cooperative targets at a distance of 1.3 m. The overall measurement standard deviation reached 14.73 µm, and the minimum Allan deviation was 189 nm at a 2.84 s averaging time. Additionally, we demonstrated 3D imaging experiments with “TIF” patterned cardboard and corridor stairs, obtained data precision better than 0.8 cm, and achieved high reliability in 3D imaging.