The invention discloses an extendable sunshade. The extendable sunshade comprises a first slide support and a second slide support, one end of the first slide support is provided with a gear box, the inside of the gear box is internally rotatably connected to a rocking bar, a cloth cylinder is arranged between the gear box and the second slide support, a front frame is arranged between the first slide support and the second slide support, the side faces of the first slide support and the second slide support are both provided with slide rails, the two ends of the front frames are both provided with limiting blocks, the insides of the first slide support and the second slide support are both provided with springs, the springs are fixedly connected to the limiting blocks, the cloth cylinder and the front frame are provided with sunshade cloth, and the bottom of the front frame is provided with a draw cord. According to the extendable sunshade, through the slide effect of the front frame on the slide rail, the forwards extending sunshade range of the sunshade cloth is adjusted, the influence of weather on the extending structure is small, the operation is simple and flexible, it is guaranteed that indoor light rays are bright but not dazzling, the indoor temperature is lowered, the load of the air-conditioner is reduced, the energy consumption is lowered, and the service life of indoor home decoration and furniture is prolonged.