Controlled　stacking　of　different　two-dimensional　(2D)　atomic　layers　hold　great　promise　for　significantly　optimizing　the　optical　properties　of　2D　materials　and　broadening　their　applications.　Here,　vertical　2D　MoS2/Bi2Te3　heterostructures　with　high　crystallinity　and　optical　quality　have　been　successfully　constructed,　through　drop-casting　2D　Bi2Te3　flakes　on　chemical　vapor　deposition　(CVD)-grown　MoS2　flakes.　Based　on　our　homebuilt　micro　Z-scan　and　pump-probe　measurement,　we　precisely　investigated　and　compared　the　nonlinear　optical　(NLO)　performance　of　an　individual　micro-sized　MoS2　flake　before　and　after　stacking　2D　Bi2Te3　nanoplates.　Moreover,　layer-dependent　ultrafast　carrier　dynamics　of　CVD-grown　MoS2　flakes　were　also　explored.　Owing　to　the　efficient　charge　transfer　from　the　monolayer　(1　L)　MoS2　to　2D　Bi2Te3,　the　1L　MoS2/Bi2Te3　heterostructure　demonstrated　excellent　NLO　performance　with　superior　nonlinear　saturable　absorption　coefficient　and　ultrashort　carrier　lifetime.　Our　work　greatly　enriches　our　understanding　of　2D　heterostructure　and　paves　the　way　for　designing　new　type　of　tunable　2D　photonics　materials　by　combining　the　optical　advantages　of　different　2D　materials.