SHANGHAI, Oct 22 (Reuters) - China's central bank on Thursday lifted its official yuan midpoint for the sixth trading day to the highest since July 2018, underpinned by solid gains in spot prices a day earlier.

The People's Bank of China (PBOC) set the midpoint rate at 6.6556 per dollar prior to the market open, 225 pips, or 0.34%, firmer than the previous fix of 6.6781. It was the strongest guidance rate since July 11, 2018.

Onshore spot yuan advanced to end the domestic session at a more than two-year high against the dollar on Wednesday, led by firmer central bank guidance and recent data showing a sustained recovery in the world's second-largest economy.

(Reporting by Winni Zhou and Andrew Galbraith; Editing by Christian Schmollinger)