The single-light-source dual-optical path visibility meter is a kind of camera type visibility meters, and its light source and optical path system directly affect the accuracy of visibility inversion. In view of the error caused by the instability of the light source and the split light path in the original system, the integrating sphere is used as the improved source of the single-light-source dual-optical path visibility meter, and the near and far reflection end is used to split an integrating sphere light source. The near and far light spots captured by the camera are extracted and brought into Koschmieder's law. The experimental results show that compared with the LED light source, the integrating sphere light source proposed in this paper reduces the uniformity error by 5%. Compared with the transmission type visibility meter LT-31 and the scattering type visibility meter VPF-730 under different visibility conditions, the root-mean-square (RMS) relative error and relative average error of this scheme are much less than 20%, which is in line with the WMO's error requirement of the visibility meters.