Abstract: The classical method of selecting ranging-codes is based on the finite field theory so that the range of selecting combination codes is much small,and it is also very difficult to obtain the enough code number and better cross-correlation performance.Therefore,an!algorithm of searching the m sequences and their preferred pairs in the global field is presented in this paper.Meanwhile,three schemes to generate the ranging codes of navigation satellites are also discussed in detail.All ranging-code sequence combinations can be gotten by using the algorithm.And then the ranging-code sequences with enough number and better cross-correlation performance can be generated from the selected Gold code family.Finally,by comparing the selected ranging-codes with GPS C/A codes on the assignable code number and auto-and cross-correlation features,the advantage of the selected ranging-codes and the feasibility of the algorithm can be illustrated preliminarily.