[en] Vacuum conditioning in the HL-1 tokamak is summarised. The gaseous impurities were reduced from 5.3 x 10^-5 Pa in 1984 to 1.1 x 10^-5 Pa in 1987. Only when the ultimate pressure is less than 1.3 x 10^-5 Pa, and the percent concentration of H₂O components less than 5%, it is suitable for initial wall conditioning of tokamak discharges. By using the GH₃₉ SS limiter, G₃ graphite limiter or sublimating Ti, the average density of C + O in HL-1 was respectively 6.1 x 10¹¹, 1.4 x 10¹² or 1.1 x 10¹² cm^-3. After sublimating Ti, O decreased nearly 24% and C nearly 16%