how to faster importing mesh in sims 4 studio

If the size of the .package is that big I'd asume it's because whatever you're creating has a lot of poly count? If that's the case, you can and SHOULD try to reduce the poly count since It won't work well in the game. Objects or CAS items with such count would make the game extremely slow and unplayable, and It's our responsability as I see it to make custom content that won't break any game out there...

If you are using blender, try the decimate modifier to lower the poly count, your cc may not look perfect but remember most of the details won't actually be that important in the game look.

i converting 3d models,and works fine in my game. is it safe to continue with that work and for others to download that?

If I was working with a mesh and it turned out more than a hundred polys or so higher than a similar EA item has I would definitely try to reduce it. If I couldn't reduce the poly enough without spoiling the appearance of the mesh I would list the poly count with the upload. That way people with computers that cannot handle high poly meshes could avoid downloading it and people with computers that can handle it could still enjoy the very nice appearance of the item.

While it is true there are some players that really need and/or want low poly items there are other players who are more concerned with the appearance of the item and they won't mind going a few hundred polys over the usual to get an item that looks really great.

The key I think is just being open about the poly count and why it needed to be higher than usual. Also, of course, you don't want to get too crazy with the poly count and make a game crasher.

If your converting models from model download sites, they are not designed for games, they are 3D rendering/animation type works not games.

you are right..
sims resource : Your creation cannot be accepted at this time because your poly counts are too high for the sims game. Object Poly counts can be no more than 1200 for each in game tile on the high detail. You will need to reduce the poly count for this item before we can accept it for publish.
i have 80k poly ;D

I'd say anything above 2k poly for a small decor item is way too much. You can easily achieve a similar Eiffel Tower "look" with a much simpler mesh with solid planes where the "beams" aren't meshed, but are achieved through transparency.

I was going to suggest what J said for the Eiffel tower item. Doing it that way would require you to remove all the vertices that lie between the big upright struts of the tower. Once those verts were gone you would put planes between them instead. Then you would create an alpha texture that looks like the lattice work between the upright struts. The rose vase could be redone so that it is not so perfectly round and the flowers could also be on an alpha how EA makes their flowers. The candles in the candle holder do not need to be quite so perfectly round and the holder itself could lose some roundness and possibly some of the detailing. If this is a 3D model you downloaded the chances are that even each of the wicks contains far too many vertices and simplifying them would be another way to shed vertices that are contributing to the high poly count.

The challenge of making things for a low poly game is working within the limits the game can manage...making something look nice with an economy of vertices.