Abstract: In ambiguity resolution,present TCAR/MCAR methods only use some combina-tions whose characters are not excellent,and they don’t fully consider all observation errors.Aiming at those disadvantages,a new TCAR/MCAR method which considers every error is deduced,and the success rates of ambiguity resolution in different baseline distances are ana-lyzed.Via the success rates the ionospheric delay is found as the key to the ambiguity resolu-tion,so we attempt to correct it and the result of the example shows that this method is able to improve it.