How can pass a data of a node's field to entityform field I have a field named "code". This hidden field stores some alfa_numeric values.

Nodes with using this data field have an entityform type as a block in page. 

How can I pass node's data values to entityforms data field as prepopulated.
You can use hook_form_alter in a custom module and pass the node field value to the value of the form item eg :

&lt;?php
  function mymodule_form_FORM_ID_alter(&amp;$form, &amp;$form_state, $form_id){
    // dpm($form);
    $node = node_load(arg(1));
    $form['field_code']['#value'] = $node-&gt;my_field[LANGUAGE_NONE][0]['value'];
  }
?&gt;


Things you need to know are:

The ID of the entity form for FORM_ID, you can get this using Get form ID module.

What the field you are populating is ? you can install Devel module then uncomment the line in the above code to inspect the form.

Where within the node object the field with the data is ? If Devel is installed you can navigate to the node and click on the Devel tab and explore the node there.

If you are using hidden fields then ['#value'] is ok but if it is a textfield then you should use ['#default_value'].

Also, this is presuming that the form is in a block on the node page, other wise node_load(arg(1)); will node work.