Anyway the 'feather' of Korean feather grass and mine do not match,too many difference
I agree. What you have shown in your photos is slightly different than what Timur has shown (although they may be related varieties).
The grass/weed you have posted seems shorter, the seeds appear to be spherical and the puffy material is finer and more cotton-like.
Would it be possible for you to pull one of these plants up (carefully) to expose the roots, and then get a closer picture of the leaves and stems. Also, if you could narrow down the area in Asia where this is growing that would help too.