Abstract: The development process of the first ultra-high vacuum prototype of HIRFL-C-SR is introduced and the results are given. The structure of the vacuum chambers designed for the prototype is described, The key standard equipments are tested and chosen.The out-gassing rate of the chamber materials in the ultimate pressure is estimated in terms of the experimental results.The effective pumping speed of the titanium sublimation pump is calculated according to the formulas and is validated by the experiment.The progress of the vacuum baking system is introduced as well.The expected pressure of 3×10^-9 Pa has been obtained and kept.It means the design of the UHV system of HIRFL-CSR project is feasible.