diff --git a/src/ifcconvert/IfcConvert.cpp b/src/ifcconvert/IfcConvert.cpp
index 45e5520dce..227557ed8f 100644
--- a/src/ifcconvert/IfcConvert.cpp
+++ b/src/ifcconvert/IfcConvert.cpp
@@ -402,6 +402,7 @@ int main(int argc, char** argv) {
 		("site-local-placement",
 			"Place elements locally in the IfcSite coordinate system, instead of placing "
 			"them in the IFC global coords. Applicable for OBJ and DAE output.")
+		("use-z-up", "Z UP. default Y UP，Applicable for OBJ output.")
 		("building-local-placement",
 			"Similar to --site-local-placement, but placing elements in locally in the parent IfcBuilding coord system")
         ("precision", po::value<short>(&precision)->default_value(SerializerSettings::DEFAULT_PRECISION),
@@ -467,6 +468,7 @@ int main(int argc, char** argv) {
 	const bool use_material_names = vmap.count("use-material-names") != 0;
 	const bool use_element_types = vmap.count("use-element-types") != 0;
 	const bool use_element_hierarchy = vmap.count("use-element-hierarchy") != 0;
+	const bool use_z_up = vmap.count("use-z-up") != 0;
 	const bool no_normals = vmap.count("no-normals") != 0;
 	const bool center_model = vmap.count("center-model") != 0;
 	const bool center_model_geometry = vmap.count("center-model-geometry") != 0;
@@ -740,6 +742,7 @@ int main(int argc, char** argv) {
 
     settings.set(SerializerSettings::USE_ELEMENT_NAMES, use_element_names);
     settings.set(SerializerSettings::USE_ELEMENT_GUIDS, use_element_guids);
+	settings.set(SerializerSettings::USE_Z_UP, use_z_up);
 	settings.set(SerializerSettings::USE_ELEMENT_STEPIDS, use_element_stepids);
 	settings.set(SerializerSettings::USE_MATERIAL_NAMES, use_material_names);
 	settings.set(SerializerSettings::USE_ELEMENT_TYPES, use_element_types);
diff --git a/src/serializers/GeometrySerializer.h b/src/serializers/GeometrySerializer.h
index 3a0c88e181..5bcf8d1854 100644
--- a/src/serializers/GeometrySerializer.h
+++ b/src/serializers/GeometrySerializer.h
@@ -53,8 +53,11 @@ public:
         /// Use step ids for naming elements.
 		/// Applicable for OBJ, DAE, and SVG output.
 		USE_ELEMENT_STEPIDS = 1 << (IfcGeom::IteratorSettings::NUM_SETTINGS + 6),
+		/// Use step Z UP .
+		/// Applicable for OBJ output.
+		USE_Z_UP = 1 << (IfcGeom::IteratorSettings::NUM_SETTINGS + 7),
 		/// Number of different setting flags.
-        NUM_SETTINGS = 6
+        NUM_SETTINGS = 7
     };
 
     SerializerSettings()
diff --git a/src/serializers/WavefrontObjSerializer.cpp b/src/serializers/WavefrontObjSerializer.cpp
index 0b5de33548..2ffd24cad6 100644
--- a/src/serializers/WavefrontObjSerializer.cpp
+++ b/src/serializers/WavefrontObjSerializer.cpp
@@ -88,7 +88,11 @@ void WaveFrontOBJSerializer::write(const IfcGeom::TriangulationElement<real_t>*
 {
     obj_stream << "g " << object_id(o) << "\n";
 	obj_stream << "s 1" << "\n";
-
+	bool isyup = true;
+	if (settings().get(SerializerSettings::USE_Z_UP) ){ //settings().get(SerializerSettings::USE_Z_UP)
+		isyup = false;
+	}
+	
     const IfcGeom::Representation::Triangulation<real_t>& mesh = o->geometry();
 
 	const int vcount = (int)mesh.verts().size() / 3;
@@ -96,7 +100,12 @@ void WaveFrontOBJSerializer::write(const IfcGeom::TriangulationElement<real_t>*
         const real_t x = *(it++);
         const real_t y = *(it++);
         const real_t z = *(it++);
-		obj_stream << "v " << x << " " << y << " " << z << "\n";
+		
+		if(isyup){	
+			obj_stream << "v " << x << " " << y << " " << z << "\n";
+		}else{
+			obj_stream << "v " << -x << " " << z << " " << y << "\n";
+		}
 	}
 
     for ( std::vector<real_t>::const_iterator it = mesh.normals().begin(); it != mesh.normals().end(); ) {