Linear CCD has been widely used in low light detection,but it’s easy to operate the device into the nonlinear region if set incorrectly.Two factors of optical response-light intensity and integration time were analyzed in the article,and experiments were conducted to test and verify CCD nonlinear effects.Because of its flux-current response,LED light was researched to determine the relationship between the output and the light intensity.Relationship between CCD output and the integration time was also researched through changing integration time.Observing the two experiment results,transistor model was used to analyze CCD optical response and linear region together with nonlinear region was compared.The results show that CCD nonlinear effects are apparent and its excellent linear region should be made full use of in application.