The methodology of six-sigma is one of process improvement’s approaches that its aim is efficiency improvement of process, stability, customers’ satisfaction and cutting deviations such as wastage, reworking and costs. Heretofore different techniques have been introduced for achieving to this aims, so that one of their most efficient is Design of Experiments (DOE). The DOE technique is a scientific method for introducing the main parameters related to a process, where specifies the optimal application of this parameters for increasing the performance and the capacity of process. In this paper, application of the DOE is illustrated in the six-sigma methodology to decrease process time of outsourcing contracts adopting of industrial services engineering of Iran khodro corporation (ISEIKCO) and will be determined the principle parameters which affect on time of this process. Also, statistical analysis will be used for specifying the counteract affect of effective parameters and are proposed an improvement approaches to decrease processing time, where finally the obtained results will confirm the time efficiency improvement of outsourcing process.