A silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) having a deep pseudo buried layer is disclosed. The SiGe HBT includes isolation structures formed in trenches, first pseudo buried layers and second pseudo buried layers, and a collector region. The first pseudo buried layers are formed under the respective trenches and the second pseudo buried layers are formed under the first pseudo buried layers, with each first pseudo buried layer vertically contacting with a second pseudo buried layer. The second pseudo buried layers are laterally connected to each other, and the collector region is surrounded by the trenches, the first pseudo buried layers and the second pseudo buried layers. The cross section of each of the trenches has a regular trapezoidal shape, namely, each trench's width of its top is smaller than that of its bottom. A manufacturing method of the SiGe HBT is also disclosed.