The invention provides a silicon-based all-optical wavelength converter comprising a first silicon bar shaped waveguide, a slit structure and a second silicon bar shaped waveguide arranged in sequence; the width of the first and second silicon bar shaped waveguides periodically changes, and different width portions are connected through a taper coupler; the waveguide cross section width can be changed, so sign symbols of phase mismatch before and after cross section width change can be opposite, thus regulating the phase mismatch, and energy can be continuously transferred from pump light to object light, thus improving conversion efficiency; the height of the slit structure remains unchanged; the cross section width of the first and second silicon bar shaped waveguides periodically changes between a first width W1 and a second width W2; the first and second widths W1 and W2 follows the formula: kW1 kW2 <0; the kW1 and kW2 respectively represent phase mismatches corresponding to the first and second widths W1 and W2. The cross section size of the silicon-based wavelength converter can be periodically changes so as to effectively regulate the phase mismatch, thus improving conversion efficiency.