Construction site is noted for its dense population, high mobility of construction workers, hard working and poor living conditions. Therefore, during the SARS spreading period, the local government put the construction site into the strictly control list in view of the outbreak of SARS. Some contractors were punished because of their poor measures taken for controlling the SARS. Under the SARS attack, for the construction firm, it is necessary to have good site environment control. The environment benefit and economical benefit due to site environment management have been elaborated in this paper. The legal duty of the contractor is also explored in view of related laws and regulations. The management framework and site environment practice are discussed in detail.