Abstract: The viscosity-temperature curve of ground tank oil viscosity 50 ℃ at 366.4 ~ 72 477.0m Pa o s in Bohai sea has been selected to conduct fitting.The results show that under the ASTM standard secondary logarithmic coordinates,the linear fitting of each sample is of good relations,the slope of each line is approximately the same,and then the heavy oil viscosity prediction formula has been further obtained.According to 50 ℃ ground oil viscosity,the other degassing viscosity under other temperatures can be predicted.Comparing the calculated dead oil viscosity at reservoir temperature with the existing PVT experimental data,through data regression,the crude oil formations containing dissolved gas viscosity prediction formula has been obtained,which can provide good reference for the development plan of heavy oil reservoirs in Bohai sea.