Abstract: To support low-carbon product development,a model of carbon footprint based on product structure is built by using modularization and lifecycle analysis methods.Sensitivity analysis is applied to determine the mapping relationships between the change of key low-carbon design parameters and carbon emission.On the basis of revising analysis results,a multi-constrained objective optimization model of low-carbon design improvement of key modular unit was established with a target of the most reduction of carbon emission which is caused by the improvement of low-carbon design parameters.Back-tracing and genetic algorithm are applied to numerically solve the problem.Finally a case study of dishwasher is given to illustrate the feasibility and applicability of this method.