Abstract: We propose a new method for ambiguity fixing between network RTK reference stations, which can improve the ratio value and success rate for the ambiguity test when ambiguity fixed needs long time passing the ratio test. Firstly, wide\|lane and L2 ambiguity, with its variance\|covariance matrix are formed from the original ambiguity by integer transformation. Secondly, LAMBDA method is used to sequentially fix the transformed block ambiguity. The results show that the new method not only can fast and reliably fix the wide\|lane ambiguity, but also improve the ratio value and success rate when ambiguity fixed correctly,which reduce the initialization time of ambiguity fixing.