In this contribution,quality control which includes number of visible satellites,PDOP and multipath of BDS+GPS integrated system in varying cut-off elevations is analyzed by a lot of real datasets,and then the performance of BDS+GPS multi-frequency RTK positioning over short baseline is evaluated.The following conclusions can be drawn: more satellites are visible in the combined BDS+GPS system,which ensures the spatial geometry intensity even in case of high cut-off elevations; With the cut-off elevation increases,the impact of the multipath effects on BDS and GPS is significantly weakened,so the AR success rate is mainly affected by the spatial geometry intensity in case of high cut-off elevations;The triple-frequency BDS-only or combined system can perform as well as that of dual-frequency,but it is not much beneficial to positioning performance; The AR success rate and positioning accuracy of BDS+GPS combined system in case of high of cut-off elevations still remain high,which will significantly improve the availability and reliability of the current RTK positioning under some challenging conditions.