Project　managers　normally　investigate　how　to　reduce　the　total　completion　time　of　projects　undertaken　subject　to　the　pre-determined　objectives.　The　purpose　of　this　paper　is　compression　of　total　projects＇　duration　subject　to　influencing　factors　such　as　cost,　time,　quality　and　risk.　In　the　present　study,　by　considering　factors　affecting　project　success　such　as　cost,　time,　quality　and　risk,　project　crashing　and　fast　tracking　are　both　employed　then　a　fuzzy　multi-objective　non-linear　model　is　proposed.　Each　project　is　associated　with　uncertainty　and　the　lack　of　consideration　of　these　uncertainties　might　lead　to　project　failure.　In　addition,　a　fuzzy　approach　has　been　employed　for　incorporating　the　uncertainties　associated　with　activities.　In　the　proposed　model,　crashing　and　fast　tracking　of　projects　were　considered　simultaneously　for　the　first　time.　According　to　a　real　case　study　considered　in　this　paper,　after　using　the　proposed　model,　the　cost　of　compression　is　also　reduced.　In　addition,　we　determined　which　activities　have　to　be　crashed　or　fast　tracked　in　order　to　attain　the　objective.　The　proposed　methodology　can　be　practically　applied　through　mega　projects　such　as　construction　and　＂Engineering,　Procurement,　and　Construction＂　(EPC)　projects　where　the　deadline　closes　to　being　achieved.　As　another　contribution,　a　unique　feature　of　the　proposed　model　is　its　capability　for　taking　both　crashing　and　fast-tracking　simultaneously　into　consideration.　©　2018-IOS　Press　and　the　authors.　All　rights　reserved.