The dynamic model of flexible manipulator arm having addition mass block on its end position is deduced in the first place,then several parameters of flexible manipulator arm impacted by its end position addition mass are enumerated,the effect of the end position addition mass on the parameters is exploded through route chart. it is favorable to subsequent analysis and computation that program calculation illustrates that the effect of the end position addition mass on the parameters is not more complex than the description by the formulas.