The invention discloses a car power amplifier housing. The car power amplifier housing simultaneously meets the heat dissipation requirement and the dustproof requirement. According to the main points of the technical scheme, a shell is connected with a movable part in a sliding manner; the movable part can retract into the shell and can extend out of the shell; a hollow cavity communicated with the inside of the shell is arranged in the movable part; and a through hole which is communicated with the hollow cavity is formed in the lateral wall of the movable part. When the power of a car power amplifier is relatively high or the environment temperature is relatively high, the movable part can extend outside, so that the total heat dissipation area of ventilation holes of the shell is increased and heat dissipation is facilitated. When the power of the car power amplifier is relatively low or the environment temperature is relatively low, the movable part can retract into the shell to prevent dust from entering the shell. The housing can relatively well meet the dustproof requirement and the heat dissipation requirement.