Abstract: Elaborated in the essay are the manufacturing and processing technologies for the Ti alloy seamless pipe,and the present situation of its application to the fields of marine engineering and oil/gas development.To meet the requirements for hi-strength,hi-toughness and hi-corrosion resistance of the pipe for oil/gas well service,based on the chemical composition of the conventional TC4 Ti alloy,a new type of Ti alloy is developed.And according to the wholeprocess optimized hot-rolling and heat treatment processes,the mini-flow and low-cost manufacturing process applicable to the large-sized Ti alloy oil well-service pipe is proposed,and then used for a trial production of the TC4-NiNb Ti alloy seamless pipe.The ambient temperature strength of the said pipe is higher than that of the TC4 Ti alloy seamless pipe by at least 100 MPa,and its mechanical properties and impact toughness are in compliance with relevant requirements for the P110 and Q125 steel grades.This mini-flow process provides a possibility for further reduce the production costs and expanding the application scope of the Ti alloy oil well pipe.