SN74CBTLV3125: SN74CBTLV3125 Pin oxidation

These pins looks fine. See [FAQ] Why do the leadframes look strongly oxidized or corroded?

The pin won't stick to the tin

the pin   is a little yellow,could you tell me  what material of PIN

The lead finish is NiPdAu (also see [FAQ] What is the thickness of Gold (Au), Palladium (Pd), or Nickel (Ni) for TI's NiPdAu lead finish?)

A roughened leadframe makes it easier for dirt to accumulate. Also, copper might migrate to the surface and oxidize.

Are you using enough flux when soldering?