diff --git a/source/module_io/read_input_item_exx_dftu.cpp b/source/module_io/read_input_item_exx_dftu.cpp
index 98c7824390..87a8edc480 100644
--- a/source/module_io/read_input_item_exx_dftu.cpp
+++ b/source/module_io/read_input_item_exx_dftu.cpp
@@ -88,7 +88,7 @@ void ReadInput::item_exx()
         read_sync_string(input.exx_real_number);
         item.reset_value = [](const Input_Item& item, Parameter& para) {
             if (para.input.exx_real_number == "default")
-            {
+            {  // to run through here, the default value of para.input.exx_real_number should be "default"
                 if (para.input.gamma_only)
                 {
                     para.input.exx_real_number = "1";
@@ -181,7 +181,7 @@ void ReadInput::item_exx()
         read_sync_string(input.exx_ccp_rmesh_times);
         item.reset_value = [](const Input_Item& item, Parameter& para) {
             if (para.input.exx_ccp_rmesh_times == "default")
-            {
+            {   // to run through here, the default value of para.input.exx_ccp_rmesh_times should be "default"
                 std::string& dft_functional = para.input.dft_functional;
                 std::string dft_functional_lower = dft_functional;
                 std::transform(dft_functional.begin(), dft_functional.end(), dft_functional_lower.begin(), tolower);
diff --git a/source/module_parameter/input_parameter.h b/source/module_parameter/input_parameter.h
index f870dd7ba0..cdee21ce49 100644
--- a/source/module_parameter/input_parameter.h
+++ b/source/module_parameter/input_parameter.h
@@ -470,7 +470,7 @@ struct Input_para
     double exx_mixing_beta = 1.0;               ///< mixing_beta for outer-loop when exx_separate_loop=1
     double exx_lambda = 0.3;                    ///< used to compensate for divergence points at G=0 in the
                                                 ///< evaluation of Fock exchange using lcao_in_pw method
-    std::string exx_real_number = "0";          ///< exx calculated in real or complex
+    std::string exx_real_number = "default";          ///< exx calculated in real or complex
     double exx_pca_threshold = 0.0001;          ///< threshold to screen on-site ABFs in exx
     double exx_c_threshold = 0.0001;            ///< threshold to screen C matrix in exx
     double exx_v_threshold = 0.1;               ///< threshold to screen C matrix in exx
@@ -485,7 +485,7 @@ struct Input_para
                                                 ///< inequality
     double exx_cauchy_stress_threshold = 1e-07; ///< threshold to screen exx stress using Cauchy-Schwartz
                                                 ///< inequality
-    std::string exx_ccp_rmesh_times = "1";      ///< how many times larger the radial mesh required for
+    std::string exx_ccp_rmesh_times = "default";      ///< how many times larger the radial mesh required for
                                                 ///< calculating Columb potential is to that of atomic orbitals
     std::string exx_distribute_type = "htime";  ///< distribute type (assuming default as no specific value
                                                 ///< provided)