In order to solve the problem that the impact for the subjective factors is great and there may be unreasonable attributes in the artillery target threat degree assessment. An objective assessment model based on preference relation is established and target threat degree sequencing can be got; Then, rough set theory is used to do artillery target threat assessment decision table attribute reduction and value reduction, which can remove the unreasonable attributes and redundant information; At last, an example shows that this method is practical and effective.