The invention relates to environment-friendly and energy-saving assembling type automatic car washing equipment in a building site. The automatic car washing equipment comprises a water pond, a car washing pump, a mud cleaning pump, a car washing pipeline, a mud cleaning 
pipe, a car washing platform, a 
pollutant discharging pipeline, an 
infrared probe and a control tank, wherein the water tank comprises a mud storing pond, a water filtering pond, a water separating pond and a water storing pond which are sequentially arranged, the car washing platform comprises a car washing table and 
pipe ditches, the 
pipe ditches are covered with a pipe 
ditch covering board, the car washing pipeline is arranged inside the pipe 
ditch, a plurality of car washing spraying heads are connected to the car washing pipeline, the mud cleaning pipeline comprises a mud cleaning main pipeline and a plurality of mud cleaning 
branch pipelines, one end of the 
pollutant discharging pipeline is connected with one pipe 
ditch close to the mud storing pond, and the other end of the 
pollutant discharging pipeline is connected with the mud storing pond. The environment-friendly and energy-saving assembling type automatic car washing equipment in the building site can simultaneously and automatically wash a car and 
discharge pollutant, the car washing working efficiency is improved, the cleaned polluting water can be used in a recycling way after being precipitated and filtered, and the water resource and the car washing cost are lowered.