The Hefei Advanced Light Facility (HALF) is a fourth-generation vacuum ultraviolet (VUV) and X-ray diffraction limit synchrotron radiation (DLSR) light source now under preliminary research. To achieve ultralow beam emittance and small beam size, the orbit of the beam in DLSR storage ring should meet the stability requirement at submicron scale. The beam position monitor (BPM) electronics measures the orbit and is hence an essential part of the beam orbit control system. We design a BPM electronics based on the MicroTCA.4 standards platform, which consists of an MicroTCA.4 module (including a chassis, a power supply, and a digital board, etc.), a customized RF front end module, and a frequency synthesizer. IQ sampling and digital signal processing algorithms are implemented to obtain turn-by-turn (TBT) data, fast acquisition (FA) data at a 10kHz rate, and slow acquisition (SA) data at a 10Hz rate. To evaluate the performance and function of BPM electronics, we conducted offline tests in the laboratory and beam tests based on the storage ring of HLS II, a light source similar to the HALF as an alternative. Test results indicate that the performance of MicroTCA.4-based BPM electronics can meet the requirements of the HALF storage ring.