Abstract: The re-entry of tools in horizontal wells can be negativelly affected by problems in removing the ball seat in multistage ball-drop sliding sleeves such as low drilling efficiency and incomplete removal. In order to overcome that, a graphene reinforced aluminum-based composite was developed to make soluble ball seat with sliding sleeve. By using graphene and silicon carbide ceramic particles and with powder metallurgy, a graphene reinforced aluminum-based composite was obtained. The composite possess characteristics of high strength, high hardness and self- rapid dissolution in saline environment, with yield strength of 469 MPa and surface hardness up to 170 HBW. The soluble ball seat made of graphene-reinforced aluminum-based composite could still maintain sealing and pressure-bearing capacity when eroded by sand-containing fracturing fluid with a sand ratio of 30% at a flow rate of 4 m³/min for 26 hrs, and its overall weight was only reduced by 2.1%. In addition, the ball seat could completely be dissolved in the 4% KCl solution at 90 ℃ when soaked in the solution for 32.5 hrs. The field test showed that the developed graphene reinforced aluminum-based soluble ball seat could satisfy the requirements of multistage sliding sleeve fracturing with high flow rate, high sand ratio and long operation time. After fracturing, the ball seat can dissolve by itself in downhole liquid environment to achieve a full-diameter borehole. The developed graphene reinforced aluminum-based soluble ball seat can provide clean and safe wellbore conditions for the second stimulation of the reservoir.