Arrival angle fluctuations of partially coherent beams have been studied in the atmospheric turbulence. Using the model of modified Von Karmon spectrum considering its inner-scale and outer-scale, generalized huygens-fresnel principle and cross-spectrum density function, the expressions of arrival angle fluctuations of partially coherent beams have been deduced in the atmospheric turbulence. The influence to arrival angle fluctuations of partially coherent beam, on the turbulence along a horizontal path have been analyzed in different turbulence scales, different turbulence intensity, different transmission distance, different source coherence parameters and different wavelength. The result shows that with the increase of transmission distance, arrival angle fluctuation is more and more small; with the increase of atmospheric turbulence scale and source coherent parameters, arrival angle fluctuation is bigger and bigger; compared with the partially coherent beam, the influence of the arrival angle fluctuation of the completely coherent beams turbulence is very small; with the decrease of the wavelength and intensity of turbulence, arrival angle fluctuation is more and more small.