The influence of the defocus state of the optical system on the phase of structured light based on sine grating, abbreviated as sinusoidal structured light, was analyzed. Based on the property that the sinusoidal structured light phase is independent of the camera's focusing state, a method of calibrating the camera in the defocus state using a phase-shifted sinusoidal-structured-light-encoded display panel is proposed. The Floyd-Steinberg Dithering algorithm is used to eliminate the structured light phase calculation errors caused by the gamma conversion of the display panel. This method makes the accurate extraction of the feature points of the calibration object under the defocus state come true. The calibration result has a reprojection error of 0.17 pixels. The calibration error of the camera focal length is within 0.39%. The calibration accuracy was improved compared to traditional methods. A solution for the calibration of cameras with a special imaging range was provided.