A method for making thermoacoustic device includes following steps. A silicon substrate having a first surface and second surface opposite to the first surface is provided. The first surface is patterned by forming a plurality of grooves substantially oriented along a first direction, wherein the plurality of grooves is spaced from each other, and a bulge is formed between each two adjacent grooves. An insulating layer is coated on the patterned surface. A first electrode and a second electrode are formed on the insulating layer, wherein the first electrode and the second electrode are spaced from each other. A carbon nanotube structure is applied on the insulating layer, wherein the carbon nanotube structure is electrically connected to the first electrode and the second electrode, the carbon nanotube structure is suspended above the plurality of grooves.