The invention relates to a heating time-adjustable electric heating lunch box. The lunch box comprises a lunch box cover, a lunch box body and a shell, the bottom of the lunch box body is provided with an electric heating element, the electric heating element is electrically connected with an external power supply, an air switch is arranged between the electric heating element and the external power supply, the lunch box cover is provided with a timer, the timer is in contact with the switch button of the air switch through a driving member, and the timer comprises a cam and a gear group cooperating with the cam and driving the cam to rotate. The electric heating lunch box can control starting and closing of the on-off of the air switch through the timer, the cam of the timer drives the driving member after the assigned time of the timer is reached in order to reset the switch button of the air switch and make the electric heating element be in a power-off state, and foods with ideal temperature can be obtained only through presetting the heating time without person watching in the heating process of the electric heating lunch box, so the electric heating lunch box has the advantages of good controllability and heating convenience.