WoodyWoo <saulmatchless@163.com> added the comment: @eric.smith @scoder @serhiy.storchaka Thank U all. I get what to do,and still think the "for in" structure should rebuilding. All three methods: import xml.etree.ElementTree as ET xmlstr=\ r'''<?xml version="1.0"?> <data> <country name="Liechtenstein"> <rank updated="yes">2</rank> <year>2008</year> <gdppc>141100</gdppc> <neighbor name="Austria" direction="E"/> <neighbor name="Switzerland" direction="W"/> </country> <country name="Singapore"> <rank updated="yes">5</rank> <year>2011</year> <gdppc>59900</gdppc> <neighbor name="Malaysia" direction="N"/> </country> <country name="Panama1"> <rank updated="yes">69</rank> <year>2011</year> <gdppc>13600</gdppc> <neighbor name="Costa Rica" direction="W"/> <neighbor name="Colombia" direction="E"/> </country> <country name="Panama2"> <rank updated="yes">69</rank> <year>2011</year> <gdppc>13600</gdppc> <neighbor name="Costa Rica" direction="W"/> <neighbor name="Colombia" direction="E"/> </country> </data>''' print(xmlstr) #orginal code root = ET.fromstring(xmlstr) for country in root.findall('country'): rank = int(country.find('rank').text) if rank > 50: root.remove(country) print("___orginal___") for country in root.findall('country'): print (country.get("name")) print("^^^orginal^^^^\n") #wrong code in my mind root = ET.fromstring(xmlstr) for country in root: rank = int(country.find('rank').text) if rank > 50: root.remove(country) print("___bad___") for country in root.findall('country'): print (country.get("name")) print("^^^bad^^^^\n") #my code root = ET.fromstring(xmlstr) index=0 count=len(root.findall("./*")) while index <count: rank = int (root[index].find("rank").text) if rank>50: root.remove(root[index]) index=index+0 count=count-1 # avoid index err continue index=index+1 print("___new___") for country in root.findall('country'): print (country.get("name")) print("^^^new^^^^\n") ---------- _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue41892> _______________________________________