Frequency estimation of sinusoidal signal is widely used in communication, radar and sonar, etc. Forasmuch as Accurate estimation of sinusoidal signal frequency, an frequency estimation method for sinusoidal signals based on quadrant discriminating and moving fitting is proposed. The period or phase step of the sampled signal is estimated preliminarily using the quadrant discriminating method. Then, the move sine fitting method and the estimated parameters are applied to processing of sequence data further. Finally, the signal period or frequency is calculated directly according to the fitted phase of corresponding sequence point. The proposed algorithm is compared with simulation accuracy of three existing interpolation algorithms based on discrete Fourier Transform (DFT), The simulation results show that when the design SNR is -5,0,5 dB, measuring frequency is about 11.432Hz with six discrete frequencies, sampling frequency is 2222.22Hz and data quantity is 5112, the mean root mean square error (RMSE) of frequency estimation of this method is respectively 2.048×10-3，1.290×10-3，0.870×10-3Hz. The mean of mean absolute error(MAE) is respectively 1.823×10-3，1.209×10-3，0.687×10-3Hz, which is lower than the errors of the other three algorithms. The proposed algorithm has higher accuracy and is closer to the Cramer-Rao lower bound (CRLB). The proposed algorithm is stable performance due to insensitive to the range of frequency.