The present disclosure discloses a method and a device for building a virtual keyboard. The method includes the steps: detecting a touch area of finger operation; determining the number of keys to be arranged in a key region of the virtual keyboard according to the detected touch area of finger operation and an area of the key region of the virtual keyboard; and arranging the determined number of keys in the key region of the virtual keyboard according to a preset strategy. The number of keys arranged in a key region of the virtual keyboard is determined in the present disclosure according to the touch area of user's finger operation and the area of the key region of the virtual keyboard so that the area of each key in the virtual keyboard is adaptable to the touch area of fingers.