The silicon doped carbon quantum dots(SDCQDs) were synthesized using 3-aminopropyl trimethoxysilane(APTMS) and glutaraldehyde(GA) as mixed precursors.The maximum absorption wavelength，fluorescence excitation and fluorescence emission wavelengths of the SDCQDs were 259 nm，245 nm and 395 nm，respectively.The quantum yield of SDCQDs was 13.60%.The XPS spectra showed that the quantum dots were rich in azomethine group and silicon oxygen bond.The fluorescent intensity of SDCQDs could be quenched by copper ions.Hence，on the basis of the relationship between fluorescence quenching ratio and concentrations of copper ions，a method was developed for the determination of copper ions in water samples by using silicon doped carbon quantum dot as fluorescent probe.Other metal ions had no function of quenching.The spiked recoveries were in the range of 91.4%-100.8%，the detection limit was 0.13 μmol/L and the relative standard deviations(RSDs) were in the range of 0.20%-0.92%.