Abstract: Model frequencies and model shapes reflect the inherent characteristics of one kind of fuel assembly. The breakdown or damage of fuel assembly have bad influence on its operation, which is one of the most important reasons for the engineering accident. Based on the multiple curves fitting of transfer function using LMS model analysis software, a hammering test of Single-Input Multi-Output（SIMO） analysis method have been performed on a kind of fuel assembly. The orders of mode frequencies and model shapes were obtained by the test as force to be single-input, and multiple accelerometers to be output. Comparing to the calculation modal, the test results are proved to be validity and reliability.