In order to detect weak targets,a design scheme of imaging system based on back-illuminated CCD（BCCD） 47-10 is presented.By analyzing the principle and parameters of CCD47-10,the hardware circuit is designed.It is composed of power module,driver module,signal processing module and data transfer module.VHDL language is used to design the logic circuit.The PC software is programmed by VC++.Finally,the experimental system is set up to image grating in dim light and the signal to noise ratio（SNR） is 72.The result shows that the system can meet the requirement of weak targets detection.