Abstract: In the process of photosynthesis, energy transfer in light-harvesting protein complexes is efficient and robust. Recent 2D electronic spectroscopes have identified the long-lived quantum coherence in several natural light-harvesting systems. Within a quantum dynamic framework, we observed optimal energy transfer due to the competition of quantum coherence and bath-induced dissipation. The optimization can behave in various parameters, including reorganization energy, temperature, spatial-temporal correlation of bath, etc. The mechanism of the trapping-free subspace is proposed to explain this optimization behavior. To address the nontrivial quantum effects, we compared results of the flux network from quantum dynamics and classical hopping kinetics. In the end, we developed the higher-order quantum kinetic equations (HO-QKE) for describing nontrivial quantum effects term by term.