The purpose of this study was to evaluate the effects of environmental parameters on the dinoflagellates cyst abundance of Gonyaulacales and Gymnodiales orders in the sediment of Oman Sea coastal regions and the Strait of Hormuz in winter and spring 2015. Dinoflagellate cyst study helps to identify key areas for  the feature bloom of harmful species. For this purpose, sediment sampling was carried out by Grab (Ekman) at 15 stations located in the Pasabandar, Ramin, Konarak, Galak and the first Tiab estuary in the Strait of Hormuz. Salinity, temperature, acidity and depth of water column were measured in each station. The sediment grain size and the total organic matter content of the sediment were measured in the laboratory and dinoflagellate cysts were isolated, identified and counted. The relationship between the environmental parameters and the species of dinoflagellate cysts was studied by the ordination method of canonical correspondence analysis(CCA). The ordination results of CCA showed that the abundance of dinoflagellate cysts was significantly affected by the environmental parameters and the sediment grain size (P<0.05). In general, the abundance and distribution of dinocysts in the winter was affected by the percentage of silt, sand, silt-clay and the total organic matter (TOM), whereas the abundance and distribution of dinocysts in the spring was affected by the temperature and depth of water, as well as the percentages of  sand, silt, silt-clay, clay and TOM.