Abstract: In order to realize the stress and strain research of the main shaft of multi-rope friction hoist, the strain detection points of main shaft device are optimized based on the improved particle swarm optimization algorithm.Firstly, the mechanical model of the main shaft device is analyzed according to the finite element simulation and modal analysis.The special points are selected initially as the strain measuring point of the main shaft device based on the simulation results.Secondly, the modal assurance criterion is selected as fitness function, and combined optimization by particle swarm optimization(POS).In order to prevent the local optimization in the optimization process the cross-operation is introduced to improve the POS.Finally, according to the optimization result of the measuring points, the variable pieces are pasted on the corresponding position of the main shaft device.The strain detection of each measuring point is realized by using the wireless strain gauge.This method provides a data basis for the following research on the fault diagnosis of main shaft and the load detection of friction hoist.