Abstract: A new algorithm,named as several-epoch algorithm (SEA) is studied in the short baseline GPS rapid positioning using several epoch single frequency phase data.Based on TIKHONOV regularization theorem,a new regularizer,which has explicitly physical meaning,is chosen to mitigate the ill-condition of the normal matrix.The accurate float ambiguity solutions and their MSEM(Mean Squared Error Matrix) are obtained using several epoch single frequency phase data.Combined with LAMBDA method,SEA can fix the integer ambiguities correctly and quickly using MSEM instead of the covariance matrix of the ambiguities.At last,the baseline vector is resolved.The effect of the new algorithm and LS is illustrated by one example.