diff --git a/lib/json2xls.js b/lib/json2xls.js
index e0a7a07..3b6e74e 100644
--- a/lib/json2xls.js
+++ b/lib/json2xls.js
@@ -53,10 +53,11 @@ transform.prepareJson = function(json,config) {
         });
         fields = Object.keys(fields);
     }
+    var fieldNames = conf.fieldNames || fields
     //cols
     res.cols = fields.map(function(key,i) {
         return {
-            caption: key,
+            caption: fieldNames[i],
             type: getType(jsonArr[0][key],types[i]),
             beforeCellWrite: function(row, cellData, eOpt){
                 eOpt.cellType = getType(cellData,types[i]);