For compatibility with present CMOS devices, the single-electron transistor (SET) is preferably made in silicon. In this paper, a Si-based SET with in-plane side gates is proposed, which is fabricated in a SIMOX (Separation by IMplanted OXygen) wafer using electron beam lithography (EBL) with high-resolution SAL601 negative e-beam resist and inductively coupled plasma (ICP) etching. Carefully controlled the process, the SET with a 70-nm-radius Coulomb island is successfully fabricated. The Rds-T characteristics of the SET indicate that the device has typical semiconductor characteristics and the co-tunneling phenomena is impossible to occur. The Ids-Vds characteristics of the SET at different values of Vg (-10 V, 0 V, 10 V) measured at the temperature of 2 K all show Coulomb staircases. And the good reproducibility of the Ids-Vds characteristics can also be realized. The corresponding dIds/dVds-Vds characteristics show the clear differential conductance oscillations at 2 K. The Ids-Vg curve at Vds = 0.1 V and Vg = 10 V approximately exhibits Coulomb oscillations. The fabrication process is quite easy and this kind of Si-based SET has the advantages of simplicity, IC-orientation and compatibility with traditional CMOS process.