For sorting purposes and consistency all the names in IMDb are stored in "lastname, firstname" format within the database itself.
Paul Newman is stored as Newman, Paul
James Earl Jones is stored as Jones, James Earl.
When displaying filmographies and film credits, the names are converted to the more common/clearer "First Last" format (i.e. Cruise, Tom is shown as Tom Cruise).
The Chinese however write their names putting the family name first. In Chow Yun-Fat's case, for example, Chow is the family name (like "Smith") and Yun-Fat is the first name (like "John").
Therefore, according to the rule above, the name is stored in IMDb as Chow, Yun-Fat and displayed in film credits as Yun-Fat Chow
By the way, a case like the above is easy to determine because there's a dash in the name, which typically identifies the first name.