The present invention discloses a manufacturing method of heat-dissipating element, including the following steps: processing a heat-dissipating element body with a bottom plate and at least two stop plates, the stop plates being disposed at two sides of the bottom plate and bending towards surface; cutting from the bottom plate of the heat-dissipating element body to form heat-dissipating element, the dissipating element at least comprising two heat-dissipating elements of same shape or of symmetric shape. The present invention also discloses a heat-dissipating element and backlight module manufactured by the above method. The heat-dissipating element, manufacturing method and backlight module thereof can maintain optimal heat-dissipation effect and save material used to lower cost.