Red mud, limestone and sandstone were used to prepare Portland cement for road. The effect of red mud addition on the structure and properties of Portland cement for road was studied. The results show that the major mineral phases of red mud Portland cement for road clinker are C3S, C2S and C4AF. Red mud based Portland cement for road with excellent properties can be prepared by grinding the clinker with 5% dehydrate gypsum. Compared with ordinary Portland cement for road, red mud Portland cement for road has a lower early compressive strength. Although red mud was dealkalized in advance(total alkali content in dealkalized red mud(by mass)＜1%), the alkali of the Portland cement for road clinker can still make adverse effect on minerals formation of Portland cement for road if the addition of dealkalized red mud(by mass) exceeds， 26%. The alkali in the sintering system exist mainly in the intermediate phase of clinker of red mud Portland cement for road in the form of K2SO4 or Na2SO4. The radioactivity specific activity of 226Ra increases along with hydration length of time increasing, 40K is just opposite, 232Th is basically unchanged. The external exposure index of red mud based Portland cement for road is 087, the external exposure indexes of it in different curing ages are all less than the limit.