The invention discloses a scouring and bleaching process of cotton-hemp blended rough yarn, which comprises the steps of pre-acid treatment, washing, rough yarn scouring and bleaching, washing, acid pickling and washing, wherein the step of scouring and bleaching comprises the following processes: impregnating the rough yarn after the pre-acid treatment and washing in scouring and bleaching liquid, wherein the bath ratio of the rough yarn to the scouring and bleaching liquid is 1:(15-25); performing program heating, wherein the start temperature is 20-25 DEG C, the heating speed is controlled at 2-4 DEG C per minute, the target temperature is set at 90-100 DEG C, and the target temperature is kept for 20-40 minutes; the scouring and bleaching liquid comprises the following substances: 3-6g/L hydrogen peroxide and 1-2g/L sodium nitrate; the pH value is adjusted to 10-11 with sodium hydroxide. The scouring and bleaching process of cotton-hemp blended rough yarn, disclosed by the invention, can obtain relatively high whiteness without reducing the strength of the cotton fiber while maintaining the good properties of cotton and hemp, so that the cotton-hemp blended rough yarn meets requirements for spinning.