We present a study of thermal stability of the top spin valve with a structure of seed Ta (5nm)/Co75Fe25 (5nm)/Cu (2.5nm)/Co75Fe25 (5nm)/Ir20Mn80 (12nm)/cap Ta (8nm) deposited at room temperature by magnetron sputtering. A vibrating sample magnetometer fixed with a heater was used to record the magnetic hysteresis loops at variational temperatures and x-ray diffraction was performed to characterize the structure of the multilayer. The exchange field Hex and the coercivity of the pinned CoFe layer Hcp decrease monotonically with increasing temperature. The coercivity of the free CoFe layer Hcf in the spin valve shows a maximum at 498K. The temperature dependences of Hex, Hcp and Hcf have also been discussed.