With the gradual increasing of utilized satellite bands, the requirement on the surface accuracy of reflectors is growing higher rapidly. The mould design and manufacture is one of the key factors of manufacturing higher accuracy reflectors. The mould properties would be influenced by temperature in the surface deviation of the Root Mean Square(RMS) and the thermal expansion deformation. A mould surface compensation formula of an offset parabolic mould is established. The compensation formula is theoretically derived, simulated and verified. Results show that the mold surface accuracy achieves 0.05 mm RMS at the curing temperature of the reflector by this compensation method; the influence of the mould’s thermal deformation on the antenna surface accuracy can be effectively weakened.