In this work, a low-frequency high-precision quadrant photodetector (QPD) with large bandwidth was studied for transponder type inter-satellite laser heterodyne interferometer of space-based gravitational wave detection. By conducting the in-depth theoretical modeling and noise analysis on the QPD, suppression strategies for the key noise sources including photodiode junction capacitance and operational amplifiers were proposed. For experimental demonstration, the preliminary QPD was fabricated and tested. The response frequency from 5 to 25 MHz, and the phase noise floor of 10 μrad/Hz1/2 at 6 mHz were experimentally achieved by the fabricated QPD, which were close to the stringent phase reading requirement of the TianQin mission.