In order to investigate the effects of graphene oxide （GO） on the thermal expansion coefficient of GAP modified spherical propellant composites， GAP modified spherical propellant composites containing GO with 0%， 0.5%， 1%， 1.5% were prepared， respectively. Fourier transform infrared spectroscopy （FTIR）， scanning electron microscopy （SEM） and differential scanning calorimetry （DSC） were used to investigate the structure， morphology and thermal properties of the composites， respectively. The effect of GO content on thermal expansion coefficient and glass transition temperature was investigated using a static thermomechanical tester （TMA）. The results showed that the addition of GO had little significant effect on the structure and thermal properties of the cured system and no chemical reaction occurred. The addition of GO resulted in a reduction to the expansion coefficient of the composites. When the content of GO is 1%， the expansion coefficient presents the greatest reduction， decreasing from 3.236×10^-4 K^-1 to 2.692×10^-4 K^-1. The glass transition temperature increased from 20.8 ℃ to 25.1 ℃ with the addition of GO content relative to the pure GAP modified spherical propellant composite.