As　is　well　known,　base　region　is　the　design　focus　of　bipolar　junction　transistor　(BJT).　Generally,　the　doping　distribution　in　base　is　non-uniform.　In　this　paper,　the　effects　of　different　Gaussian　dopings　in　the　base　on　bulk　temperature　distribution,　temperature　dependences　of　current　gain　and　cut-off　frequency　are　first　studied.　It　is　found　that　current　gain　and　cut-off　frequency　of　BJT　have　positive　temperature　coefficients,　and　the　temperature　in　bulk　is　high.　Then,　the　effect　of　Ge　composition　distribution　on　these　device　parameters　is　investigated.　It　is　found　that　the　SiGe　heterojunction　bipolar　transistors　(HBTs)　with　box　Ge　composition　distribution　and　trapezoidal　Ge　composition　distribution　have　negative　temperature　coefficients　of　current　gain　and　cut-off　frequency,　and　have　good　bulk　temperature　distributions.　Furthermore,　the　SiGe　HBT　with　trapezoidal　Ge　profile　has　higher　current　gain　and　cut-off　frequency,　and　its　temperature　insensitivity　is　kept.　The　good　trade-off　is　made　among　the　magnitudes　of　current　gain　and　cut-off　frequency,　temperature　sensitivity　and　bulk　temperature　distribution.