diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index 5441c78b34..91e0664fe7 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -2233,7 +2233,14 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
         this->placeholder_parser().set("plate_name", new ConfigOptionString(print.get_plate_name()));
         this->placeholder_parser().set("first_layer_height", new ConfigOptionFloat(m_config.initial_layer_print_height.value));
 
-        //BBS: calculate the volumetric speed of outer wall. Ignore pre-object setting and multi-filament, and just use the default setting
+        //add during_print_exhaust_fan_speed
+        std::vector<int> during_print_exhaust_fan_speed_num;
+        during_print_exhaust_fan_speed_num.reserve(m_config.during_print_exhaust_fan_speed.size());
+        for (const auto& item : m_config.during_print_exhaust_fan_speed.values)
+            during_print_exhaust_fan_speed_num.emplace_back((int)(item / 100.0 * 255));
+        this->placeholder_parser().set("during_print_exhaust_fan_speed_num",new ConfigOptionInts(during_print_exhaust_fan_speed_num));
+
+        // calculate the volumetric speed of outer wall. Ignore pre-object setting and multi-filament, and just use the default setting
         {
 
             float filament_max_volumetric_speed = m_config.option<ConfigOptionFloats>("filament_max_volumetric_speed")->get_at(initial_non_support_extruder_id);