A parabolic trough solar receiver, also called the heat collection element (HCE), is the key component to reduce the heat loss and improve the optical-thermal efficiency in parabolic trough solar system. Testing and operating results show that expect for the major heat loss through glass envelope, heat transfer through the receiver’s end components, metal bellow, Kovar and support bracket, have a larger heat flux that is able to affect the accuracy of laboratorial thermal test and reduce the thermal efficiency in the actual operation. In this paper, the structures and heat transfer mechanisms of inner-bellow and outer-bellow end structures are analyzed at first. Then, 3-D models are performed to simulate the heat losses process by CFD software. In order to investigate heat loss influence in real operating environment, the end heat losses are simulated under different vacuum levels and wind speeds. Modelled results show receiver’s end should be covered by heat insulator during the laboratorial test to avoid end influence, except for the inner-bellow receiver without flange. Because of a vacuum annulus, either outer or inner bellow structure increases a small heat loss while the flange or support bracket lead to a large heat loss. Simulation also shows all the end components are sensitive to the changes of vacuum level and wind speed, which should be completely covered in the solar field.