The accumulation of space charges on the dielectric films of agricultural greenhouses in proximity to HVDC overhead lines poses significant challenges to predicting and controlling the electromagnetic environment. This paper investigates the impact of surface resistivity on the surface charge dissipation characteristics of three common dielectric films: Polyethylene (PE), polyolefins (PO), and anti-fog Polyethylene (AFPE). The surface resistivity of the films is measured employing the PDC method. An experimental platform using a needle electrode is established to charge the dielectric film. The surface charge distribution on the dielectric film is measured during dissipation. The experimental results reveal that films with lower surface resistivity exhibit pronounced surface charge movement, whereas those with higher resistivity show less movement. The surface conduction charging mechanism of dielectric films is analyzed based on the experiment. This study lays the groundwork for developing a charge calculation model that accounts for charge movement along the surface.