The geometry structure of microphone array shape is important for their performance, and plays the key factors impacting for external noise source identification. The simulation of the array directivity, angle resolution and other performance of cross-array and hexagonal-array (37 elements), rectangular-array (36 elements) were performed. The results indicate that cross-array has the best directivity is 71.6 dB, hexagonal-array has the best space symmetry and also is able to suppress grating lobe. The comparison of main lobe width with array element number variation shows that increasing element number to improve angular resolution is not helpful when the number is greater than 100.Through analyzing the relationship between main lobe width and frequency concludes that the output signal distortion degree of three kinds of array is practically the same.