The D-S evidence theory is an excellent method of information fusion.Because of the difference which is caused by the sensors

it is essential to deal with the evidence with a method of weighed D-S theory.Presently

the study of the weighed D-S theory is confined to synthetic methods

and the study on how to obtain better weight value is also rarely covered.In fact

the definition of the weight values is fundamental to the process of weight-synthesizing the evidence.Considering the disadvantages of the weighed D-S theory

a best method of obtaining evidence weight value is presented.After elaborating the thoughts of the new method

an excellent weight value is provided by establishing an optimized model and improving the particle swarm algorithm.Compared with the comparison methods

this evidence theory proves more effective by making simulation test.