The change of the turbulent fields during a mesoscale system which occured on August 7,1990 in Tongxian,the suburb of Beijing is analyzed. The results show that during the development of mesoscale system the turbulent parameters in the surface layer changed significantly. The local turbulent transportation accelerates the development of. mesoscale system in some respects, and besides the local turbulent spectra have some obvious variations during the incursion of mesoscale systems.