The present invention provides a compound of 5GY 8.5 / 3 pigment and a method of preparing real color block, the composition of the compound by weight is: CSC-A base material 995-1005 portions; PY138, the content of the pigment is 27%, 4.34-4.44 portions; PG7, the content of the pigment is 20%, 0.84-0.94 portions; PY42, the content of the pigment is 60%, 6.08-6.18 portions. The CSC-A base material is mainly composed of acrylic copolymer, the content is 30-40%. TiO2 is selected as a main white pigment, the content is 18-22%. The contrast ratio of the base material is 0.90-0.96, stormer viscosity is 90-100KU, when the incident angle is 85, the lossiness is 5-10. The compound of the invention has high weatherability and stability, better ratio reproducibility, the raw material and the process are in accordance with environmental protection requirement and standard of lower VOC and non-VOC; the real color block has a small color difference compared with the standard value in the theoretical model, the accurate degree of the color is high, having simple process, and high practical value.