A real-time imaging data acquisition （DAQ） system for pn-junction Charge-Coupled Devices （pnCCD） was developed， incorporating multi-thread processing and multi-frame image superposition techniques to address the specific operational characteristics of pnCCDs. To fulfill the high-speed DAQ requirements for real-time data acquisition and caching， DDR3 memory was employed to receive scientific data from the detector box. The host computer utilized the queue operations functionality of LabVIEW to implement multi-threaded processing for data acquisition， storage， and image superposition. Additionally， real-time image processing modules with multiple operational modes were designed. Experimental results demonstrated that the DAQ system effectively met the requirements across various pnCCD operational modes. Real-time image processing enabled rapid determination of the focusing camera's imaging position， facilitating efficient completion of key experimental procedures， such as focus adjustment and positive axis determination， within the X-ray calibration facility. The system exhibited stable and reliable communication， showcasing exceptional flexibility and portability.