The invention discloses a system for dust reduction and haze removal for a construction site, and a construction method thereof. The system comprises a water storage water tank, a water conveying hoseand mist spray heads, wherein the water storage water tank is formed by welding a steel plate, water is supplied to the outside through a high-pressure water pump, and the turn-on and turn-off of thehigh-pressure water pump are controlled through an electromagnetic valve; a high-pressure metal hose is adopted as the water conveying hose, the water conveying hose is composed of a vertical pipeline and a horizontal pipeline, the vertical pipeline and the horizontal pipeline are installed and configured on a tower body and a cargo boom of a tower crane separately, and the vertical pipeline is connected with the horizontal pipeline through a universal joint; and a plurality of the mist spray heads are configured, and uniformly installed at the lower side of the horizontal pipeline of the water conveying hose, and the turn-on and turn-off of the mist spray heads are controlled through an electromagnetic valve. According to the system for dust reduction and haze removal for the construction site, and the construction method thereof, compared with the prior art, water mist is sprayed by virtue of the large arm of the tower crane to realize a dust reduction and haze removal technology for the construction site, and safety and reliability are achieved; and after implementation, the safety can be improved and the management efficiency can be increased, so that a good environment is provided for the site.