Heterojunction　phototransistor　(HPT)　can　produce　high　current　gain　and　its　fabrication　process　is　compatible　with　that　of　heterojunction　bipolar　transistor　(HBT).　In　this　paper,　a　HPT-type　Ge　quantum　dot　photodetector　with　Ge-dot　multilayers　incorporated　in　the　base-collector　junction　was　grown　by　UHV/CVD.　TEM　and　DCXRD　measurement　showed　good　crystal　quality　of　the　material.　Then　a　two-terminal　HPT-type　Ge　quantum　dot　photodetector　was　fabricated　to　improve　its　emitter　efficiency　with　a　heavily　doped　polysilicon　layer　as　the　emitter.　At　room　temperature,　I-V　measurement　showed　that　the　dark　current　density　of　the　HPT-type　Ge　quantum　dot　photodetector　was　low　and　the　breakdown　voltage　was　high.　Under-8V　bias,　a　photo-responsivity　of　4.47　mA/W　and　0.11　mA/W　was　achieved　at　1.31　μm　and　1.55　μm,　respectively.　Compared　with　a　reference　PIN　detector　with　the　same　quantum　dot　layer,　the　responsivity　was　improved　by　a　factor　of　104　and　78　at　1.31　μm　and　1.55　μm,　respectively.