没有什么可以看的，NXOPEN直接录制一下导出STEP就可以了。
录制出来自己挑需要的代码拿过来改一下。

 1 NX9+VS2012
 2 
 3 #include <NXOpen/Part.hxx>
 4 #include <NXOpen/PartCollection.hxx>
 5 #include <NXOpen/Session.hxx>
 6 #include <NXOpen/Step214Creator.hxx>
 7 #include <NXOpen/DexManager.hxx>
 8 
 9 Step214Creator *step214Creator1;
10 step214Creator1 = theSession->DexManager()->CreateStep214Creator();
11 
12 step214Creator1->ObjectTypes()->SetSolids(true);
13 
14 step214Creator1->SetInputFile("D:\\test5.prt");
15 
16 step214Creator1->SetOutputFile("D:\\test5.stp");
17 
18 step214Creator1->SetFileSaveFlag(false);
19 
20 step214Creator1->SetLayerMask("1-256");
21 
22 NXObject *nXObject1;
23 nXObject1 = step214Creator1->Commit();
24 
25 step214Creator1->Destroy();