The conformation of polymers at interface profoundly influences the interfacial properties. Quartz crystal microbalance with dissipation (QCM-D) is a newly developed technique to detect polymer behavior at interface in real time. In this article, we mainly review our QCM-D studies. Our focus is on temperature induced collapse and swelling of tethered polymer chains, pancake-to-brush transition and mushroom-to-brush of polymer chains.