Extendable seat frame and furniture thereof

A furniture, comprising:

• a first cushion,
• a second cushion, and
• an extendable seat frame comprising:
• a fixed base;
• a seat frame main body, configured to move relatively above the fixed base;
• and
• an extension apparatus, configured to be rotatably connected to the fixed base and rotatably connected to the seat frame main body so as to enable the extendable seat frame to switch between a retracted state and an extended state,
• wherein the extension apparatus comprises at least an extension part, one end of the extension part is rotatably connected to an end of the seat frame main body that is away from an extending direction, and the extension part is configured to drive the extension part to flip in response to the seat frame main body moving towards the extending direction,
• wherein the first cushion is placed above the seat frame main body, the second cushion is placed above the extension part, an upper surface of the first cushion and an upper surface of the second cushion are on a same horizontal plane.