For this study we have conducted the experiments to find out the effect of mixture of Spirulina and Yeast on the rearing performance of Eri-silkworm Philosamia ricini in respect of cocoon weight and shell weight of cocoon parameters. We have grouped the worms along with their control and then the experimental groups were treated with the different concentration and dosages of mixture of Spirulina and Yeast specially to find out the effect on the cocoons parameter (Cocoon weight, Shell weight). Then the collected data's were subjected to statistical analysis. All the results were found to be significant. It was found that average Cocoon weight (3.80 gm) was highest under treatment of 300 ppm concentrations with thrice a day doses and average Shell weight (0.63 gm) was highest under treatment of 300 ppm concentrations with thrice a day doses.