We　investigate　theoretically　how　the　intermodal　dispersion　and　the　fiber　length　influence　the　formation　of　ultrashort　pulses　in　a　dual-core　fiber　laser.　Our　simulation　using　the　Ginzburg-Landau　equation　found　that　stable　self-starting　of　mode-locking　can　be　achieved　with　a　fiber　length　deviating　from　integer　multiples　of　the　linear　coupling　length.　Furthermore,　the　intermodal　dispersion　will　not　lead　to　pulse　splitting,　in　contrast,　it　will　induce　asymmetry　in　the　pulse　shape　and　increase　the　modulation　instability.　Consequently,　a　filter　is　found　necessary　to　stabilize　the　mode-locking　operation　when　the　fiber　length　is　longer　than　the　linear　coupling　length.　(C)　2016　Elsevier　B.V.　All　rights　reserved.