Abstract: In this paper, a concept of locus factor is introduced to measure the fitness differences among/between the order-1 schemata at a certain locus. According to the relationship between locus factor and order-1 building block, the ability of the linear-weighted coding employed to a linear fitness function to generate order-1 building blocks is analyzed. An upper limit of the locus factor at a particular locus in terms of the weights is given. The results show that, in order to guarantee the calculation accuracy, there always exist loci at which locus factors are very close to 1, not matter what the weights are. As a result, the local search efficiency of the linear-weighted-encoded genetic algorithms employed to a linear function is unavoidably low.