Abstract: Double-pass compression tests were carried out on the MMS-200 thermomechanical simulator to obtain static-recrystallization curves of offshore platform steel F550.By using a combined method of dilatometry and metallography,dilatometric curves of continuous cooling of F550 were measured,and dynamic CCT curves were obtained.Transformation process of austenite during continuous cooling and microstructure of the transformed products were studied.These tests could provide references for the on-site rolling process of F550.