The use of hydraulic fracturing in shale gas exploitation has generated substantial amount of flowback and produced water (FPW), and ecological risk of these highly complex chemical mixtures has raised worldwide concern. Herein, an integrative effect-directed analysis (EDA) and nontarget screening (NTS) workflow was developed to identify and prioritize main toxicants in the treated FPW (T-FPW). The workflow included sample extraction and fractionation, zebrafish embryo toxicity tests, target and nontarget chemical analyses, and toxicity prioritization and confirmation using toxicological priority index (ToxPi). Results showed that less hydrophobic compounds (log K