The paper uses a modified theoretical model and a modified spring model to establish the calculation model of load distribution under make up torques and axial loads by analyzing the load condition of the drill collar Law of load distribution has been analyzed in detail The effect of thread taper, frictional coefficient caused by different lubricants and spring coefficient of the thread on load distribution of the threaded connection have been pointed out In addition, some main measures for improving the load condition of the connection and reducing the stress concentration are presented The maximum axial load of connection has also been obtained by a simple mechanical model