A method for displaying an arc menu index, applied to a mobile terminal comprising a display screen that supports a touch-screen operation, comprising: receiving (101, 501) a menu expanding instruction after a start button of the arc menu index is clicked by a user; and expanding the arc menu index on the display screen according to the menu expanding instruction; wherein the arc menu index comprises: an index operation area, an index pointer, and index characters; the index operation area is an area that is compassed by an arc border line displayed on the display screen and display edges intersecting the arc border line, and the index characters are arranged along the arc border line; and the index pointer is located in the index operation area and is configured to indicate a selected index character; wherein after receiving the menu expanding instruction, the method further comprises: detecting a thumb-index finger webspace of a palm of the user, wherein the thumb-index finger webspace is used to determine a circle center of the arc border line; wherein expanding the arc menu index on the display screen according to the menu expanding instruction comprises: expanding the arc menu index on the display screen according to the menu expanding instruction and the detected thumb-index finger webspace, wherein the arc border line of the arc menu index is an arc that is drawn on the display screen with the thumb-index finger webspace as the circle center, and wherein the circle center is a point outside the display screen; wherein detecting a thumb-index finger webspace of a palm of the user comprises: detecting, by using a gravity-sensing apparatus of the mobile terminal, an inclination which exists when the user holds the mobile terminal; calculating the thumb-index finger webspace of the palm of the user according to the detected inclination and a preset algorithm, wherein a position relationship between the inclination and the thumb-index finger webspace of the palm of the user is set by using the preset algorithm. receiving (101, 501) a menu expanding instruction after a start button of the arc menu index is clicked by a user; and expanding the arc menu index on the display screen according to the menu expanding instruction; wherein the arc menu index comprises: an index operation area, an index pointer, and index characters; the index operation area is an area that is compassed by an arc border line displayed on the display screen and display edges intersecting the arc border line, and the index characters are arranged along the arc border line; and the index pointer is located in the index operation area and is configured to indicate a selected index character; wherein after receiving the menu expanding instruction, the method further comprises: detecting a thumb-index finger webspace of a palm of the user, wherein the thumb-index finger webspace is used to determine a circle center of the arc border line; wherein expanding the arc menu index on the display screen according to the menu expanding instruction comprises: expanding the arc menu index on the display screen according to the menu expanding instruction and the detected thumb-index finger webspace, wherein the arc border line of the arc menu index is an arc that is drawn on the display screen with the thumb-index finger webspace as the circle center, and wherein the circle center is a point outside the display screen; wherein detecting a thumb-index finger webspace of a palm of the user comprises: detecting, by using a gravity-sensing apparatus of the mobile terminal, an inclination which exists when the user holds the mobile terminal; calculating the thumb-index finger webspace of the palm of the user according to the detected inclination and a preset algorithm, wherein a position relationship between the inclination and the thumb-index finger webspace of the palm of the user is set by using the preset algorithm. detecting a thumb-index finger webspace of a palm of the user, wherein the thumb-index finger webspace is used to determine a circle center of the arc border line; wherein expanding the arc menu index on the display screen according to the menu expanding instruction comprises: expanding the arc menu index on the display screen according to the menu expanding instruction and the detected thumb-index finger webspace, wherein the arc border line of the arc menu index is an arc that is drawn on the display screen with the thumb-index finger webspace as the circle center, and wherein the circle center is a point outside the display screen; wherein detecting a thumb-index finger webspace of a palm of the user comprises: detecting, by using a gravity-sensing apparatus of the mobile terminal, an inclination which exists when the user holds the mobile terminal; calculating the thumb-index finger webspace of the palm of the user according to the detected inclination and a preset algorithm, wherein a position relationship between the inclination and the thumb-index finger webspace of the palm of the user is set by using the preset algorithm. detecting, by using a gravity-sensing apparatus of the mobile terminal, an inclination which exists when the user holds the mobile terminal; calculating the thumb-index finger webspace of the palm of the user according to the detected inclination and a preset algorithm, wherein a position relationship between the inclination and the thumb-index finger webspace of the palm of the user is set by using the preset algorithm.