•Three-dimensional pseudo potential lattice Boltzmann model is built up to study boiling on two-tier hierarchical structured surface.•Mechanism of accelerated bubble departure on hierarchical surfaces with upward-orientation secondary pillar is revealed.•Lateral-orientation secondary structures can deteriorate heat transfer and bring larger flow resistance.•Hierarchical structured surface with upward-orientation secondary pillars achieves best boiling performance at high wall temperature. In this paper, pool boiling on two-tier hierarchical structured surface is investigated with three-dimensional LB method. Two-tier pillar structures with different scales are designed, termed as primary and secondary pillar, respectively. On the hierarchical surface with upward-orientation secondary pillars, the bubble departure is promoted. And, the heat transfer can be improved by increasing the primary pillar spacing and enhancing surface wettability. Increasing the height of secondary pillar is favorable for enhancing capillary wicking, but can also bring greater flow resistance. On the hierarchical surface with lateral-orientation secondary pillars, the heat transfer is limited by the large flow resistance. With the enlargement of primary pillar spacing, the impact brought by flow resistance is moderated, and the heat flux can be enhanced. Finally, the boiling performance regarding the effect of wall temperature is concerned, where the structured surface with upward-orientation secondary pillars show the better boiling performance than other structured surfaces.