In order to avoid the disadvantages of existing connection mode of pipe jacking segments， effectively improve the segment connection construction efficiency, and reduce the risk and environmental pollution, a progressive tensioning technology of Macalloy bar used in the corners of segments of T221 Large Crosssection Rectangular Pipe Jacking Tunnel at Havelock Station on Thomson East Coast Line in Singapore is introduced. The results show that: (1) The tensioning technology of Macalloy bar is suitable for the connection of large crosssectional rectangular pipe jacking segment. (2) The new grouting cement and grouting equipment are used in the posttensioning process, which is an improvement for traditional tensioning technology. (3) The posttensioning technology is easily operated with low risk and can effectively enhance the overall stability of the tunnel and avoid air pollution, noise pollution and light pollution.