Hello,
It is good. The problem is solved. There is an option "Size Constraint" at the opening of .3ds file that adapts the scale at the opening of the model. But it did not work (...). So I uninstalled and reinstalled Blender. Since it works.
Now, I created my model in 3D using Metasequoia a character GameGuru as a guide ... Then I 3ds backup, then I import it into Blender with 1000 for "Size Constraint". And my scale is retained.
So finally I had a "bug" (I think) with Blender.
Thanks for your help.
K.