Not only is single frequency receiver structure simple and cheap,but also cycle slip isnt detected and repaired for single epoch,but the ambiguity success rate is not high,so ambiguity resolution of single frequency-single epoch is the hot spot of research for the high-precision positioning of Global Navigation Satellite System(GNSS).The performance of single frequency-single epoch ambiguity resolution for Global Positioning System (GPS) only having Medium Earth Orbit (MEO) satellites is limited.However,performance of single frequency-single epoch ambiguity resolution for BeiDou Navigation Satellite System(BDS),having Geosynchronous Orbit (GEO),Inclined Geosynchronous Satellite Orbit(IGSO) and MEO satellites,is different to GPS,because of the particularity of its satellite constellation design.With the constantly development and improvement of BDS,the single frequency-single epoch positioning applications of BDS will also be more and more widely,so the analysis of current BDS and BDS/GPS single frequency-single epoch ambiguity resolution performance is of great significance.The paper analysed BDS single frequency single epoch ambiguity resolution performance from the perspectives of Position Dilution of Precision(PDOP),Ambiguity Dilution of Precision(ADOP),the number of satellite,ambiguity success rate and the precision of baseline vector et al,for the BDS data which had different baseline length(0.05 km,5 km and 10 km,15 km) and different period of time (day and night,the ionosphere effect is different) from the Hong Kong station and Xuzhou region,at the same time compared with GPS and BDS/GPS.The conclusions of single frequency-single epoch ambiguity resolution of short baseline are as follows: Regardless of day and night,the BDS single frequency-single epoch ambiguity resolution performance is better than that of GPS,and during the day the baseline length which can be calculated (referring to a baseline with a success rate greater than 96%)is about 5-7km; BDS single frequency single epoch ambiguity resolution performance at night is better than the day,and the baseline length calculated at night can reach 10 km; GPS and BDS combined system can make up the deficiency of single system and greatly improves single frequency-single epoch ambiguity resolution performance,and When the baseline length is 15 km,single frequency-single epoch ambiguity can also be fixed.