# coding: utf-8

from lxml import etree as ET

users = ET.Element('users')
user = ET.SubElement(users, 'user')
name = ET.SubElement(user, 'name')
name.text = u'张三'
age = ET.SubElement(user, 'age')
age.text = u'25'
age.attrib['bod'] = '1986.8'
sex = ET.SubElement(user, 'sex')
sex.text = u'男'

print ET.tostring(users, pretty_print=True, xml_declaration=True, encoding='utf-8')

# write to file:
tree = ET.ElementTree(users)
tree.write('users.xml', pretty_print=True, xml_declaration=True, encoding='utf-8')

 效果如下（输出的XML是格式化的）：