To study the applicability of the forward analysis method based on uniform design under incomplete metrical information, a steel truss is designed and its model parameters are updated. The principal factors of model updating are analyzed and determined on condition that a few of data is measured. The mechanical characteristics of the steel truss joints are simulated by a kind of beam with variable cross-section. The value range of identification results is determined by confidence interval. Three kinds of uniform design program, which are the full-factor program, the nesting program and the multistep program, are used to correct the design parameters of the steel truss. The results show that the model updating factors and their levels determined by above methods are accurate and effective, and the results of model updating by the multistep uniform design program is the most reasonable one. When the mechanical model of a real structure is updated, the factors of model updating should be determined accurately and draw a clear distinction between the primary and the secondary. Multi small-scale uniform design programs should be constructed. And the model should be updated with multistep using these small-scale programs to reduce workloads and avoid irrational model updating solutions. At last, based on the lessons and experiences of the study, a set of methods and its calculation procedure, which are suit for model updating of large complicated structures, are summarized and described.