Based on the analysis of relationship between the geometric dilution of precision (GDOP) and the geometry layout of constellation

a new fast satellite selection method

which is called geometry satellite selection approach (GSSA)

is proposed for multi-constellation satellite navigation system.The operation of satellite selection of the proposed method is operated on the premise that the positioning requirement must be met and on the principle of uniform distribution of satellites.Simulation results show that the decrease in computation load of GSSA is more than 99% in contrast with the traditional optimal GDOP method

and the constellation GDOP obtained by GSSA can meet the demand of navigation and positioning.At the same time

the number of selecting satellites also is little

and the satellite selection is simple and rapid.And it is satisfied to the real-time capability and accuracy demand of satellite selection of satellite navigation system.