A solar mid-temperature evacuated tube collector, which was applied in a new seawater desalination system with multi-stage evaporation and recovery processes, was designed and tested. This collector can be viewed as a mid-temperature steam generator for providing steady steam with a temperature exceeding 130 degrees C. The collector can harvest solar energy only by improved all-glass evacuated tubes with low emissivity, and there is no need for solar concentrator that was applied in most mid-temperature solar collector. Therefore, a lot of cost can be saved and the system was low-cost. A series of experiments were carried out to investigate the effects of operation parameters including steam temperature, solar irradiance, weather conditions and volume of steam drums on the operation performance of the solar collector. The experimental results confirmed that the solar collector has an excellent collecting efficiency and can supply sufficient mid-temperature steam for a long time. This research proposed a low-cost solar collector for steam generator and lay a foundation for the further study on the entire seawater desalination system.