The Spanish midfielder, 30, joined Watford from Fiorentina on a four-and-a-half-year deal in January 2016.
He played 17 times in all competitions during his first season.
But in August 2016 he moved to Valencia on a season-long loan, returning to Spain where he had previously played for Atletico Madrid, Valladolid, Mallorca and Celta Vigo.
Guizhou Hengfeng Zhicheng currently sit 11th of the 16 teams in the Chinese Super League after 16 games of the season.
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Mario Suarez has left Watford to join Chinese side Guizhou Hengfeng Zhicheng FC for an undisclosed fee.