Abstract: The present optimal sensor placement is based on single-object criterion in the bridge health monitoring and structure modal test. A new method for optimal sensor placement is presented based on multi-criterion. Using the multi-object optimization algorithm, the satisfying solution (not necessarily optimal in the sense of strict mathematics) of the sensor placement is carried out using Pareto genetic algorithm. The genetic operator and coding precept are designed in this paper. Front side of Pareto solution is obtained at the end of the optimal calculation, proving the feasibility of the proposed method.