In response to the problem of the development of micro-nano pore throats in low-permeability reservoirs，the difficulty in the stripping and activation of crude oil，and the difficulty in utilization，the carbon-silicon quantum dot oil displacement agent was synthesized by solvent evaporation and thermal decomposition method. The structure of the synthesized carbon-silicon quantum dots was characterized by transmission electron microscopy（TEM），Fourier transform infrared spectroscopy（FT-IR ）and X-ray diffraction（XRD）. The temperature resistance，salt tolerance，interfacial activity，wettability and oil displacement performance of the carbon-silicon quantum dot oil displacement agent were investigated. The results showed that the quantum dots were spherical with a particle size of about 4 nm and good dispersion. XRD identified the（002）crystal plane of carbon and the（111）crystal plane of silicon of carbon-silicon quantum dots，which were in an amorphous state. FT-IR indicated that the surface of the quantum dots contained hydroxyl，carboxyl and amino groups，which could form hydrogen bonds with water molecules，improving the stability of the fluid. Under the condition of temperature of 135 ℃ and salinity of 300 g/L，the fluorescence spectrum of the quantum dots did not change significantly，exhibiting good temperature and salt tolerance. When the mass fraction of the quantum dots was 0.3%， the carbon-silicon quantum dots could reduce the oil-water interfacial tension to 0.92 mN / m，and could change the wettability of the rock surface to water-wet. The imbibition efficiency of the quantum dot oil displacement agent was 47.4%，being twice as big as that of the simulated formation water. NMR T2 spectra identified that the quantum dots could reach the micro-pores（1—10 ms）. On the basis of water flooding，oil recovery rate being of 63.95%，the injection of 0.5 PV carbon-silicon quantum dot oil displacement agent with mass fraction of 0.3% could enhance the recovery rate by 22 percentage points. The developed carbon-silicon quantum dot oil displacement agent is significant in enhancing oil recovery in low permeability reservoirs，which provides a good reference for efficient development of oil fields.