At present,China's economy is in rapid growth. The scale of engineering construction is increasing significantly and a number of major construction engineering projects have been completed or put into use. So the engineering management practice is facing new challenges with each passing day. In the meanwhile,our scholars are constantly summarizing what they have learnt in these activities and gradually establishing their own engineering management theory system,in which exploring the core thought of engineering management theory system becomes critical. By studying our engineering management theory and practice,this paper preliminarily sums up the core thought of the engineering management as "people-oriented, harmony between nature and humanity,collaborative innovation,building a harmony among people,society and nature", and a comprehensive definition of engineering management is made, with a hope to help the research on engineering management theory system.