Abstract: Assembly and cone assemble are employed between jointed pants for meeting the requirement of self centring.The fastenning capacity of rotator screwed joint with cone assembly can not be calculated according to traditional method,because it is not only related to elastical deformation of jointed parts but also to friction condition and slide condition between contact cone surface under simulation conditions of the geometry and assembly technique.A model test has been conducted to research the mechanical behaviour of the jointed parts in assembling and loading process.The load deformation relation of jointed parts reveals the difference between the plane assembly and the cone assembly.The relation of the former is linear and that of the latter nonlinear.In this research the loose condition of joint structure was defined experimentally as that the strain of cone parts equals to zero and the correlated load is named for loose load(or bearing capacity).Based on the test results the cone assembly jointed structure increases loose load owing to the friction factor.We have been predicted loose load of real jointed structure in an aeroengine by means of the model test and investigated the factors which have influence on bearing capacity.