Background & Aims of the Study: In this study three types of starch such as wheat, corn and potato were used as natural coagulants for turbidity removal of wastewater in stone cutting industry using jar test and their performance was compared with that of alum.Materials & Methods: This study is an analytical-applied. Natural wastewater from stone industry was used. The conventional jar test apparatus was utilized in all the coagulation-flocculation experiments. To evaluate the effect of gelatinized starch, the solution was prepared in both autoclaved and non-autoclaved forms. The effect of pH and coagulant doses were investigated in this study. Results: It was found that with regard to the effect of control sample from autoclaved starches, potato starch with a pH of 6 had the highest removal rate with 4.78% and among non-autoclaved starches, wheat starch with a pH of 7 had the maximum turbidity removal rate with 9.53%.Conclusions: The results showed that the non-autoclaved wheat starch has more efficiency in turbidity removal from wastewater in stone cutting industry than other starches.