A display apparatus having a display panel, a humidity DETECTION method thereof and a GAMMA curve calibration method are provided. A humidity detection method and a gamma curve calibration method for the display panel of the display apparatus are also provided. The humidity detection method for the display panel includes: displaying a test pattern via the display panel; projecting an incident light to the test pattern of the display panel via a light source to generate a diffraction light; and detecting the diffraction light via a light detector to obtain a humidity information of the display panel. Therefore, a gamma setting of the display panel may be adjusted via the humidity information of the display panel.