The paper aims to study the local features and factors of sediment fractional composition formation in the coastal zone of Koktebel Bay. The paper uses in situ data and the results of granulometric composition analysis of sediment samples from the swash and beach zones of Koktebel Bay to reveal that the beach sediments on the shoreline in the swash zone were represented by coarse gravel with the inclusion of medium and fine gravel. The material in the western and central parts of the coastal zone of the bay was moderately and poorly graded, while in the eastern part it was well graded. The granulometric composition of the beach material differed for the central and rear sections. The sediments in the central parts of the beaches were mainly represented by coarse gravel (27%) and coarse sand (26%) with inclusions of fine gravel (18%) and medium sand (14%). The material of gravel-sand beaches in the eastern part and the gravel beaches in the western part were well graded, while the beach material in the central study part was poorly graded. In the rear section of the beaches, the material was poorly graded and consisted mainly of coarse gravel, the portion of which decreases from the western part to the eastern one. In the samples from the rear part of the beaches, an increased proportion of silty material (1-13%) was noted. The features of the fractional composition of beach sediments are determined by the interception and retention of gravel material by numerous structures located directly in the shoreline, as well as by the supply of clay-sandy material as a result of wave abrasion of natural cliffs and its accumulation in the central section of the beaches as their width increases.