#$%^&*AU2020101056A420200723.pdf#####ABSTRACT The disclosure relates to a method for preparing a novel anti-tumor indoleamine 2,3-dioxygenase (IDO) inhibitor of formula (I). A compound prepared by the method has obvious inhibition activity on tryptophan metabolism. [R1]m N Cy1-(CRaRb)- Cy2 Y (I)