With the rapid growth of optoelectronics technologies, photodiodes (PDs) has been widely used in optical measurement systems, color measurement and analysis systems, etc. To meet most of the measurement requirements, the determination of PD spectral responses is very important. The goal of this paper is to develop a high-accuracy and cost-effective spectral response measurement system for PDs. In this paper, the proposed system contains a grating-based spectral filtering module, an amplifier module, and a digital-signal-processing (DSP) based platform. In the spectral filtering module, a single-grating monochromator based on a Czerny-Turner configuration is first analyzed and simulated, and then the experiments are conducted to check if the measurement accuracy is satisfactory. In the measurement system, optoelectronic signals from the PD under test are acquired from the amplifier module and the DSP-based platform is developed to communicate and manipulate the measured data. Through comparison with the measurement data from a commercially available system, it is found that our approach gives quite satisfactory results.