A 25Gb/s variable-gain amplifier (VGA) based on 0.18μm SiGe BiCMOS process was introduced for high-speed communications. The proposed VGA consists of a VGA core, an output buffer and a bias circuit. The core circuit of the VGA adopts an improved Gilbert structure to increase the gain dynamic range of the circuit. Meanwhile, the VGA achieves the broadband characteristic by utilizing inductive peaking technique to overcome the large parasitic capacitances. The post-simulation results show that the VGA exhibits a maximum gain of 20.15dB and a -3dB bandwidth (BW) of 26.8GHz, which can support a data rate up to 25Gb/s. The VGA consumes a power of 26.4mW from 3.3V supply voltage and occupied an area of 1120μm×1167μm.