In this paper, the best theoritical measurement position of single and straight tube Coriolis massflow meter is analyzed.In practical engineering condition, noise affect is important to the conclusion of the measurement,the Maximum Likelihood Estimation is used in order to get rid of the noise affect.We simulate the signal estimation in different SNR(signal to noise ration)conditions, the result shows that the best measurement position is related with the SNR.This conclusion is approved by our experiment.