A control system for construction machinery includes an upper camera installed in a driver cabin to photograph the front of the driver cabin, a lower camera installed in a vehicle body to photograph the front of the vehicle body, a work apparatus posture detection portion configured to detect a posture of the work apparatus connected rotatably to the vehicle body, an image processing portion configured to synthesize first and second images captured from the upper camera and the lower camera into one image, and configured to transparency-process at least one of the first and second images in the synthesized image according to the posture of the work apparatus detected by the work apparatus posture detection portion, and a display device configured to display the synthesized image transparency-processed by the image processing portion.