Abstract:  Based on a multiple sourcing strategy, a research is conducted on the multiechelon supply chain configuration (SCC) problem. Supply chain with uncertain number of multiple supplier options (such as more than two options) is studied. Sourcing proportion control factor (SPCF) is proposed as a multiple sourcing control mechanism. An approach based on ANP and TOPSIS is put forward to calculate the SPCF. Service time and actual sourcing proportion are adopted as two major decision variables to establish an SCC model for multiechelon supply chain. An improved Genetic Algorithm using mixed coding method of integer and real variable is proposed to solve the problem. Both the model and the algorithm are verified by demonstrative cases. At last, sensitivity analyses are conducted with a series of SPCF and several managerial insights drawn.