The interaction process between 1.06 m wavelength Nd:YAG long pulse laser with a millisecond pulse width and the MOS pixel of frame transfer area CCD image sensor and its hard damage mechanism are studied by the finite element method. The thermal-mechanical coupled modeling for long pulse laser irradiation of a MOS pixel is established, and the distributions of temperature and stress are obtained. The results show that the spallations between O layer and S layer appear due to the S layer radial stress on the surface exceeding the compressive strength under the action of the long pulse laser, then it will extend to the entire layer before melting by radial stress,axial stress and hoop stress. Hard damage of pixel occurs as spallation, and one pixel or an array of pixels in the laser irradiation area of CCD sensor is completely in failure. This paper could provide foundation for both laser-induced damage and protection of CCD image sensor.