Because the influences of the moisture in hydrocarbon or oil on the apparent thermodynamic behavior is small in each unit in refining company, hydrocarbon-water phase balance is focused and vapor-liquid is neglected in design. Hydrocarbon-water balance calculation was discussed and the deviation between calculated results and experiment data was obtained by Aspenplus for accuracy confirmation. The moisture control of gas fractionation and diesel hydrogenation in refinery were calculated and compared with industrial operation data.The results show that Aspenplus calculation as a calculation basis in design and process has directive significance to control moisture in hydrocarbon and explain moisture “abnormal” behavior.