Serious desertification caused by human activity and climate change, in addition to water loss and soil erosion related to Pisha sandstone in the Mu Us sandy land, lead to severe scarcity of soil and water resources, which causes worse local agricultural conditions accordingly. Many physical properties of Pisha sandstone is complementary with that of sand, Pisha sandstone is therefore supposed to be blended to enhance water productivity and arability of sandy land. The root zone water quality model 2 (RZWQM2) was calibrated and validated based on 2year experimental data for composite soils prepared at three ratios of Pisha sandstone to sand (1∶1, 1∶2 and 1∶5), and then used to estimate potential yield (Yp) and rainfed potential yield (Yp(r)), along with yield gap (YG(r)) of corn (Zea mays L.) by using the weather data from 1990 to 2013 in Mu Us sandy land. The mean simulated Yp(r) of corn in the compound soil at a ratio of 1∶2 (Pisha sandstone: sand) was significantly higher than that of the compound soil at 1∶1 and 1∶5 ratios, respectively. There was no difference in the simulated Yp(r) between those of the 1∶1 and 1∶5 ratios of Pisha sandstone to sand. The mean simulated Yp(r) of corn was 2551kg/hm2, 3527kg/hm2 and 2924kg/hm2 and the YG(r) was 6071kg/hm2, 5096kg/hm2 and 5698kg/hm2 at 1∶1, 1∶2 and 1∶5 ratios, respectively. The results showed the potential of Pisha sandstone as amendment on improving corn yield in Mu Us sandy land. Further research into the longterm effect of Pisha sandstone on soil chemical, biological properties and soil microbial community structure is required to gain a better understanding of the mechanism of Pisha sandstone as amendment for increasing crop yield in Mu Us sandy land, China.