The work aims to improve the picking efficiency and cargo space occupancy under the pick-to-light system (PTL). With certain PTL as the object of study, a picking optimization model aiming at the order completion, cargo space occupancy and concentration ratio was proposed. A bionic algorithm of model solution based on binary particle swarm optimization (BPSO) and genetic algorithm (GA) was designed. According to the test and optimization results, the order completion, cargo space occupancy and concentration ratio of the PTL based on BPSO were higher than those of the GA. In conclusion, the optimization model that gets the solution based on BPSO is more suitable for the actual PTL-based manual picking operation, and the utilization and picking efficiency of cargo space regarding warehousing operations have been improved.