A thermochromatic element includes a sealed enclosure, an isolation layer and a first heating element. The isolation layer is received in the sealed enclosure that divides the sealed enclosure into a first chamber and a second chamber. The first heating element is located adjacent to the first chamber. The first heating element includes a carbon nanotube film including a number of carbon nanotube linear units and a number of carbon nanotube groups. Each carbon nanotube linear unit includes a number of first carbon nanotubes substantially oriented along a first direction, and are spaced from each other and substantially extending along the first direction. The carbon nanotube groups are combined with the carbon nanotube linear units by van der Waals force. The carbon nanotube groups between adjacent carbon nanotube linear units are spaced from each other in the first direction.