A mold for forming tilt boss includes a slider part, a main part and a core pin. The slider part is formed with a tilt groove. The main part is formed with a tilt channel. When the slider part and the first main part are engaged, a tilt-boss forming cavity is formed. The tilt-boss forming cavity is communicated with the tilt channel and coaxial with the tilt channel. The core pin penetrates the tilt channel and one distal portion thereof is slidably engaged with the tilt groove, another distal portion thereof is protruded into the tilt-boss forming cavity. When the slider part is separated from the main part for allowing the core pin to be moved from a high point to a low point of the tilt groove, the core pin is downwardly moved along the tilt channel.