In this paper, we present an improved technology of making multi-mode polysiloxane waveguides. Through this kind of improvement, we can solve these problems such as reducing the number of air bubbles, demoulding, uncuring of the core layer, the chemical reaction between the core layer and the cover layer,etc. Finally, more than 80% of waveguides made by us can be successful, but before the improvement of the technology we can only have less than 40% successful waveguides. The longest waveguides can be 22.5 cm in length, compared with the 21 cm of previous ones. The propagation loss of the waveguides is 0.21 dB/cm (850 nm) by cutting back method, but before the improvement we can only have a loss of 0.3 dB/cm (850 nm). So the improvement of the technology is important in optical waveguides making.