We present the formation process of a filament in NOAA active region 12765 from 2020 June 5 to 8, using observations from the New Vacuum Solar Telescope, the Solar Dynamics Observatory, and the Global Oscillation Network Group. We found that intermittent small-scale magnetic reconnection occurs at the northern part of the filament, and the small-scale magnetic reconnection shows the characteristics of the oscillatory reconnections. During the magnetic reconnection process, a large amount of material is continuously injected into the filament channel. Furthermore, there are bidirectional inflow and outflow, current sheets, and bright cusp-shaped structures. The velocities of the material injections range from 17 to 183 km s(-1) with an average velocity of about 57 km s(-1). A total of 53 material injections were found from 03:10 UT on 2020 June 5 to 00:10 UT on June 8. The total mass carried by the injection events is about 7.39 x 10(14) g, and the total kinetic energy released through magnetic reconnection is approximately 3.09 x 10(21) J. The projection area of the filament increased from less than 1 x 10(2) Mm(2) to around 7 x 10(2) Mm(2). We conclude that the filament is formed by direct material injection into the filament channel due to the small-scale magnetic reconnections.