Abstract: The article deals with the viscsaoity calculation problems arising as heave thick and sticky crude oil is diluted.It shows with dataobtained through experiements that, of the few experiences formulars, the double logarithm formular is the most applicable, with an under 20% viscosity error in premeasurement。The diluding concentration changing in line with double logarithm has provided basisfor calculating the oil delivered thin and thick mixed in the same line.