Frequency wave-number analysis （f-k analysis） is often taken to estimate the slowness and azimuth of sismic signal in seismic array. There are different algorithms of f-k analysis and in Some special cases they lead to quite different results. For example, as being applied to the WRA array of Australia which is different from many other short period arrays by employing broadband seismic recordings at its substations, the standard f-k algorithm usually yields incorrect estimations of azimuth and slowness. It is found in this paper that the error is caused by the spectral leakage effect of FFT and may be avoided by applying a highpass filter to raw data before f-k. After comparing the time domain approach of estimating azimuth and slowness in the f-k method with the frequency domain, it is shown that the time domain approach actually is not less accurate or efficient than the improved frequency domain approach, and in the case of signal-to-noise ratio is very low, the results obtained from the time domain approach are more reliable.