thanks Michael, it really work.
and another problerm is when i export step from MOI to MAYA the "Nurbs export option" does not have an option like turn z-up to y up. the obj export option has.
but it does't matter, I just turn -90 degree on x-axis in maya or use the second ways you told me and it's all OK.
and I hope there is an option to set y-up or z-up system in MOI, men always get lazy, haha.

Hi qibentie, there is also an option to relabel the axis directions in MoI - for that go to Options > View > Axis labels.

Using that dialog you can set whatever you want for the axis direction labels, like y for elevation or whatever. But it will only change how coordinates are displayed to you and how x,y,z entered coordinates are interpreted, it won't change file reading or writing.

- Michael