A Ti:sapphire regenerative amplifier developed recently as a key part of the whole on-developing table-top TW laser system is reported. Experimentally, its energy and temporal performance under the condition of free-running is investigated: the slope efficiency of 10% and the output pulse energy as high as 4 mJ are achieved under a pumping energy of 45 mJ; The build-up time of the output laser pulse is steadily 350 ns and its repetition rate is 10 Hz. From these indexes it shows that the cavity structure and the optical setup of the regenerative amplifier are good and its steady operation makes the injection and amplification of the seed pulse reliable.