The invention discloses a side support structure for auxiliary installation equipment of an air conditioner indoor unit. The installation equipment includes a base plate and a lifting machine. The side support structure includes a first side support, a second side support, a third side support, a fourth side support and an electric push rod which are arranged outside the lifting machine. The telescopic end of the electric push rod is hinged to the first side support, the motor end of the electric push rod is hinged to the lifting machine, the first side support and the second side support arein adjacent connection and in linkage, the second side support and the third side support are in adjacent connection and in linkage, the third side support and the fourth side support are in adjacentconnection and in linkage, second castors are arranged at the bottom ends of the first side support, the second side support, the third side support and the fourth side support, and clamping and fixing structures are arranged on the second side support, the third side support and the fourth side support. The side support structure can be automatically unfolded by one-key operation, is convenient to operate, does not occupy too much space, is convenient to fold, collect and move, and is good in side support stabilization effect, the risks of damage to equipment and indoor units can be reduced,and the safety and practicality are improved.