Aiming at the multi-row facility layout problem with uncertain location and number of horizontal and vertical passages,a multi-row facility layout optimization method based on IAGA was proposed.The constraint of the maximum aspect ratio of the facility was considered,a layout optimization model was established to minimize the weighted average value of logistics cost,no-load cost of handling equipment and floor area cost.Then,an improved adaptive genetic algorithm (IAGA) based on flexible bay structure coding was designed to solve the model.Self-adaptive adjusting crossover probability,self-adaptive selection crossover operator (two-point crossover operator and single parent one-point crossover operator),basic bit mutation operator aiming at compartment structure and facility numbering arrangement respectively were adopted in the IAGA to improve its convergence speed and searching ability.Finally,the validity of the IAGA was verified by case study.