Potato has become one of the primary cash crops in the arid region of the Loess Plateau. However, what and how cereal crops to rotate with potato is better for the farmer’s income and environment is unclear now. 11 potato based rotation systems were simulated in Yulin, using EPIC model based on local information. Results showed 1) Though mean potato yield decreased from 6.84 to 5.38 t/hm2, the mean value of farmer’s gross income increased from 12807 to 20185 Yuan/hm2, when the frequency of potato increased from 0.25 to 0.50 for potato based rotation sequence. 2) By comparing, spring maize was better to increase potato yield, while it used more water than foxtail millet and broomcorn millet; Foxtail millet was one of the better preceding crops for potato, and its effects on potato yield was depended on its sequence in potato based rotation system. 3) Comparing with spring maize/potato system, foxtail millet/potato and spring maize/potato/foxtail millet/potato were two better rotation systems to use soil water sustainably and to increase farmer’s gross income for a long period in the arid region of the Loess Plateau.