The present invention provides a liquid crystal display device and brightness compensating method. The liquid crystal display device includes: a liquid crystal display panel; a touch sensor, configured to convert a press position and a press force of a user into an electrical signal; a touch control board, configured to scan and analyze electrical signal; a mainboard, configured to receive the scanned electrical signal and transmit a drive voltage instruction and a compensation voltage instruction; a logic board, comprises a code storage device storing a grayscale compensation table and an electrical level controller providing the liquid crystal display panel with a compensation voltage according to compensation voltage message, the compensation voltage is configured to make a rotation angle of liquid crystals of a press region greater than a rotation angle of liquid crystals of a non-press region.