Abstract: Described here in the paper are the main aspects of the Φ340 mm steel pipe hydrostatic testing machine newly-developed by Tianjin SERI Machine & Equipment Co.,Ltd.,covering the key technical data,the process flow,the operating principle,and the functions and structures of the key equipment units.The hydro-testing machine combines the technological and structural advantages of the similar machines currently-used both at home and abroad,and above all,features a four-beam frame structure which is quite different from the conventional single-beam or double-beam frame structure.