WDR5 is an essential protein for enzymatic activity of MLL1. Targeting the protein-protein interaction (PPI) between MLL1 and WDR5 represents a new potential therapeutic strategy for MLL leukemia. Based on the structure of reported inhibitor WDR5-0103, a class of ester compounds were designed and synthetized to disturb MLL1-WDR5 PPI. These inhibitors efficiently inhibited the histone methyltransferase activity in vitro. Especially, WL-15 was one of the most potent inhibitors, blocking the interaction of MLL1-WDR5 with IC50 value of 26.4nM in competitive binding assay and inhibiting the catalytic activity of MLL1 complex with IC50 value of 5.4μM. Docking model indicated that ester compounds suitably occupied the central cavity of WDR5 protein and recapitulated the interactions of WDR5-0103 and the hydrophobic groups and key amino greatly increased the activity in blocking MLL1-WDR5 PPI.