电荷耦合器件(CCD)是成像系统的关键器件，CCD器件的点扩展函数(PSF)是整个成像系统PSF的重要部分。采用背部入射、部分耗尽CCD，分析了载流子在CCD中的运动过程，推导了计算CCD的PSF的解析公式。对CCD进行物理建模，用蒙特卡罗方法进行粒子跟踪模拟计算得到了PSF，并能和解析公式计算得到的PSF很好的吻合。系统分析计算了CCD的主要特性参数，如响应度、线性度和调制传递函数（MTF）等。模拟研究了入射光波长和CCD自由层宽度对CCD的PSF的影响，结果表明较窄自由层宽度和长波易得到较好的PSF。

Charge coupled device (CCD) is a pivotal module of imaging system. The point spread function (PSF) of CCD is an important part of the PSF of imaging system. A backilluminated , partially depleted CCD is studied. The movements of the carriers in the CCD are analysed. The PSF are simulated based on MonteCarlo method. The simulative PSF can well match analytical PSF which are also computed. The main characteristics of CCD are analyzed，such as responsibility,linearity and modulation transfer function. The influences to PSF caused by the change of wavelength and fieldfree region are simulated, which show that better PSF can be attained by smaller fieldfree region or longer wavelength.