I am using Femap 11.2.2, when I am trying to model a surface with a dimension of 100*100m, Femap won't form one surface, only 4 edge curves are there. How to solve this issue
FEMAP does not directly have a limitation, however the Parasolid geometry engine that FEMAP uses does. The limitation however is not really on the size of geometry, but rather the coordinates. To maintain accurate precision when doing its modeling operations, Parasolid requires that all geometry is contained within a "box" of +/-500. Obviously that would not work for everyone so FEMAP implements a "Geometry Scale Factor"... which you can find and adjust on the Geometry/Model tab of the File->Preferences command. By default, FEMAP ships with this set to 0..Inches. That means that a scale factor of 39.37 is used (39.37 inches = 1 meter). You might have changed this to Meters (1.0) or Millimeters (1000.0) or set up a custom factor yourself. In any case, you should think of the size of the limiting box as 500 times whatever scale factor you have chosen (39.37*500= +/-19687)
Since you said that you are modeling a surface in Meters, I assume you may have set the scale factor to Meters also. Given that, you should still be able to model a 100x100 surface... but not if you place it too far away from the origin. Again, it is the coordinates that matter, not just the size of the geometry.
Hope this helps.