This　paper　considers　a　free　terminal　time　optimal　control　problem　governed　by　nonlinear　time　delayed　system,　where　both　the　terminal　time　and　the　control　are　required　to　be　determined　such　that　a　cost　function　is　minimized　subject　to　continuous　inequality　state　constraints.　To　solve　this　free　terminal　time　optimal　control　problem,　the　control　parameterization　technique　is　applied　to　approximate　the　control　function　as　a　piecewise　constant　control　function,　where　both　the　heights　and　the　switching　times　are　regarded　as　decision　variables.　In　this　way,　the　free　terminal　time　optimal　control　problem　is　approximated　as　a　sequence　of　optimal　parameter　selection　problems　governed　by　nonlinear　time　delayed　systems,　each　of　which　can　be　viewed　as　a　nonlinear　optimization　problem.　Then,　a　fully　informed　particle　swarm　optimization　method　is　adopted　to　solve　the　approximate　problem.　Finally,　two　free　terminal　time　optimal　control　problems,　including　an　optimal　fishery　control　problem,　are　solved　by　using　the　proposed　method　so　as　to　demonstrate　its　applicability.　©　2017　Elsevier　Inc.