Disclosed herein is a composition of polyarylene thioether prepared by combining 0.001 to 10 parts by weight of kaoline of the mean particle diameter of 0.03 to 2 .mu.m with 100 parts by weight of polyarylene thioether having the repeating unit of ##STR1## as the main constituent. The composition of polyarylene thioether has a high crystallization rate and forms a minute spherulite structure. Moreover, the composition having a short molding cycle at the time of melt molding, generates a small amount of the flash and gives the molded products excellent in mechanical properties.Disclosed herein also is a composition prepared by further combining an inorganic filler and/or a fibrous filler with the above-mentioned composition of polyarylene thioether.