Ti TES-based superconducting single-photon detectors with different dimensions between 5 μm×5 μm and 20 μm×20 μm were developed. The measured system detection efficiency （η_sys） is 72% at 1550 nm， and energy resolution （ΔE） is 0.26 eV by integrating an optical cavity during the TES fabrication. Based on the two-fluid model， we extract the key parameters （i.e.， temperature sensitivity， current sensitivity， heat capacity， et. al） of Ti TES-based superconducting single-photon detectors with different dimensions， and calculate the effective response time and ΔE， which are consistent with the measured ones. The obtained results show that it''s possible to realize high η_sys and ΔE by optimizing TES dimension and critical temperature， paving the way for high performance single-photon detectors at telecommunication band.