During the construction of underground salt cavern gas storage,the ca vity-building pipes are easy to bend due to the harsh working environment.A co m bination of several fiber Bragg gratings (FBGs) with a specific arrangement on t he outer wall of the pipe can be used to measure the bending shape of the pipe, but the pipe diameter will affect the accuracy of the bending reconstruction.In order to find the relationship between reconstruction accuracy and pipe diamete r,this paper used FBGs which is pasted on the same plain line of pipe wall to i nvestigate pipeline bending reconstruction based on finite element simulation an d sensing experiment,the finite element simulation results are compared with th e experimental results,and the error analysis is carried out.The test data sho ws that FBGs can realize the bending reconstruction of the pipe shape,and for t he pipes with the same wall thickness,as the pipe diameter increases,the relat ive error of the pipe deflection increases from negative to positive as the diam eter increases.The relative error of the pipe deflection with a diameter of 32mm when bent is close to 0point,among the 4different diameter pipes tested,t he bending reconstruction effect is the best.