The present invention relates to a composition for preventing tissue adhesion which comprising a bio-compatible hyaluronic acid and a polymer compound. More specifically, the invention is a composition containing hyaluronic acid which has not been modified by a chemical crosslinking or other chemical modification a method for preparing the same, and a composition for adhesion prevention with superior efficacy.The composition of the present invention for preventing adhesion exhibits a physical barrier function and a new adhesion prevention function whereby thrombus formation, which is the basis of adhesion, is inhibited. Unlike conventional compositions which simply mix polymeric substances that function as physical barriers, the present invention performs a more effective role as a physical barrier by undergoing decomposition, absorption and excretion after a certain period inside a human body, does not interfere with healing of scars following surgery, and exhibits superior effects since application to areas of surgery is convenient.