With the wide application of precise radiotherapy techniques in the treatment of tumor,the research of radiotherapy bed is receiving more and more attention.To achieve the aim that the workspace and the dimensions of the structure of the radiotherapy bed can meet the requirement in actual use,the multi target coordinated mechanism parameter optimization method for radiotherapy bed was introduced.In the research,the kinematics analysis of the radiotherapy bed was firstly carried out,the precise analysis of the workspace was taken on the double universal joints parallel radiotherapy bed,combining with the other inverse solution constraints.Then the influence of workspace by changing the rule of geometric parameters was obtained,which could provide the basis for the parameter optimization of the radiotherapy bed.For the problem of improving the strength and rigidity of the Hooke joint,a method of optimizing the initial mounting angle of the Hooke joint was proposed.Considering the workspace,the forces on it and the Jacobian matrix condition number,the objective function of the universe average of condition number and the fluctuation of condition number was constructed at the same time,the specific optimization of radiotherapy bed parameters was carried out.Finally,the parameters of the radiotherapy bed were obtained with the smaller condition number with uniform distribution of the Jacobian matrix in the whole workspace.According to the above,the multi target coordinated parameters optimization method for radiotherapy bed can reduce the Jacobian matrix condition number within limits.With the method,the radiotherapy bed can get the reasonable workspace and structure after the parameters are optimized,and can meet the requirement of actual use.