S259 slurry balanced shield machine, manufactured by Herrenknecht AG of Germany, was used to bore a tunnel crossing the Yangtze river in Chongqing, China. After the construction of the tunnel was completed, the slurry balanced shield machine was refurbished so as to be used for the trial tunnel of No. 4 bid section of phase 1 project of line 1 of Chengdu Metro. By reducing the diameter, the shield machine was rebuilt into a shield machine of the same type. In the paper, the refurbishment of the slurry shield machine is presented.