Unexpected curves and try to obtain solid

Test_loft.3dm (131.1 KB)
Test_loft.gh (34.5 KB)

Unexpected curves appear and solid is failed to obtain.

Cap Holesin the end is what you want?

The unexpected curves still exist.
Is there some method to get a smooth solid

You could use Fit Curve and try to hide iso-curves after bake.

Test_loft_re.gh (32.7 KB)

I bake it using rhino7 with shaded view, and am not sure whether it is caused by the rhino version difference.
Test_loft4.3dm (296.4 KB)

I’ve already mentioned…

This curve is still remained and could be viewed in different 3d modelling software.

That seam was produced by the positions of your profile curve seams. Try to relocate them to one of discontinuity points…

Like this…

Test_loft_reV2.gh (35.0 KB)

Test_loft_reV2 (1).3dm (390.2 KB)

It seems 2 unexpected curves appear on the bottom of this solid.

Those are parts of your very bottom profile curve where your loft starts…
I think you have no idea about how the loft command works for your geometry.