It is not easy to choose a target enterprise in muddy water. We should consult the financial statements of listed companies, collect their temporary announcements, media reports and official website information, form an information map, simulate the information chain of these companies, find their logical nodes, and then comprehensively sort out relevant information through field research, investigation of related parties, upstream and downstream enterprises, customers and competitors, and industry experts. And find out the defects in the evidence chain. In the process of investigating Huishan Dairy, Muddy Water used drones to photograph pastures and production bases, and even disguised as customers to obtain relevant information and evidence. Its means are far from being comparable to those of general auditing and investment institutions.