Coccidiosis is one of the most economically important diseases affecting the poultry industry. Currently, anticoccidial drugs used in veterinary clinics show many deficiencies, and new control measures are urgently needed. This study presents an anticoccidial herbal powder “Shi Yin Zi”, which consists of Cnidium monnieri (L.) Cuss, Taraxacum mongolicum Hand.-Mazz., and sodium chloride. In chickens infected with Eimeria tenella, supplementation with “Shi Yin Zi” powder for 3 d prior to infection or treatment with “Shi Yin Zi” powder after infection could improve the survival rate and relative growth rate and alleviate the pathological changes in the cecum, liver, and kidney. “Shi Yin Zi” powder could recover the levels of alanine aminotransferase, creatinine, albumin, and triglycerides in serum. The hemorrhage occurrence and total number of oocysts in feces were reduced. The anti-coccidial indexes reached 165 for the prophylactic effect and 144 for the therapeutic effect. The anti-coccidial effects were equal to positive controls (monensin and sulfamlopyrazine). These results suggest that “Shi Ying Zi” powder possesses a potent anticoccidial effect and exhibits the potential to control E. tenella infection.