An adjusting method of display parameter and a liquid crystal display (LCD) system are provided. The adjusting method includes: obtaining a first luminance value and a second luminance value when a LCD panel displaying a minimum grayscale image and a maximum grayscale image respectively; based on the first luminance value, the second luminance value and a standard Gamma curve of the LCD panel, obtaining each target luminance value conforming to the standard Gamma curve and corresponding to each grayscale; based on the target luminance value of each grayscale and a relationship between grayscale voltage and luminance obtained in advance, obtaining a target grayscale voltage of each grayscale; and adjusting a grayscale voltage of each grayscale to be the target grayscale voltage of the grayscale to thereby achieve Gamma adjustment. By the above method, automatic adjustment of display parameter for the LCD panel can be achieved.