The failure cause of the linkage-clevis bolt of civil aircraft main landing gear was analyzed recently, and it was estimated that the greatest impact load which the clevis bolt was able to support was 698 MPa while descending. The stress distribution of every meshing thread of the clevis bolt was calculated and analyzed by Yamamoto method. The finite element model of the linkage-clevis bolt was built by finite element analysis method, and the stress and strain fields of all meshing threads were analyzed. The impact load on helical effect and effect of contacting location of threads was analyzed. An important basis is provided for inspection and life prediction of the aircraft landing gear.