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When the receiver cannot demodulate satellite signal transmission time,positioning can be completed with a combination of code phase measurement and auxiliary information.That is coarse time navigation(CTN).Assistantinformation includes ephemeris,priori position and coarsesignal transmission time.For the GPS systems,requirement of the position and timeprecision is 100 km and 1min.This paper attempts to determine the allowed priori position and coarse time error range of BDS and has realized the GPS/BDS coarse time navigation algorithm and carried out experimental verification using the measured data of IGS CUT0 station.The results show that BDS,GPS andBDS / GPS coarse time navigation positioningprecision is equivalent to their pseudo-range positioning precision.Dual systemcoarse time navigationcan effectively improve positioning precision,which is betterthan the precision of single system pseudo-range positioning or coarse time navigation.Conclusion is that BDS / GPS coarse time navigationis an effective method without pseudo-range and that dual system navigation is easier to receive enough visible satellites.