<p>这是一个命名空间问题。这是有效的:</p>
<pre><code>from xml.etree import ElementTree as ET
XML = """<?xml version="1.0" ?>
<ItemLookupResponse xmlns="http://webservices.amazon.com/AWSECommerceService/2010-11-01">
<OperationRequest>
<HTTPHeaders>
<Header Name="UserAgent" Value="TSN (Language=Python)"></Header>
</HTTPHeaders>
<RequestId>96ef9bc3-68a8-4bf3-a2c7-c98b8aeae00f</RequestId>
<Arguments>
<Argument Name="Operation" Value="ItemLookup"></Argument>
<Argument Name="Service" Value="AWSECommerceService"></Argument>
<Argument Name="Signature" Value="gjc4wRNum3YT82app1d06vMIDM7v44fOmZTP8Uh3LqE="></Argument>
<Argument Name="AssociateTag" Value="sneakick-20"></Argument>
<Argument Name="Version" Value="2010-11-01"></Argument>
<Argument Name="ItemId" Value="810056013349,810056013264"></Argument>
<Argument Name="IdType" Value="UPC"></Argument>
<Argument Name="AWSAccessKeyId" Value="AKIAIFMUMJLJOOINRVRA"></Argument>
<Argument Name="Timestamp" Value="2012-01-03T21:26:39Z"></Argument>
<Argument Name="ResponseGroup" Value="ItemIds"></Argument>
<Argument Name="SearchIndex" Value="Apparel"></Argument>
</Arguments>
<RequestProcessingTime>0.0595830000000000</RequestProcessingTime>
</OperationRequest>
<Items>
<Request>
<IsValid>True</IsValid>
<ItemLookupRequest>
<IdType>UPC</IdType>
<ItemId>810056013349</ItemId>
<ItemId>810056013264</ItemId>
<ResponseGroup>ItemIds</ResponseGroup>
<SearchIndex>Apparel</SearchIndex>
<VariationPage>All</VariationPage>
</ItemLookupRequest>
</Request>
<Item>
<ASIN>B000XR4K6U</ASIN>
</Item>
<Item>
<ASIN>B000XR2UU8</ASIN>
</Item>
</Items>
</ItemLookupResponse>"""
NS = "{http://webservices.amazon.com/AWSECommerceService/2010-11-01}"
doc = ET.fromstring(XML)
Item_elems = doc.findall(".//" + NS + "Item") # All Item elements in document
print Item_elems
</code></pre>
<p>输出:</p>
^{pr2}$
<p>更接近您自己代码的变体:</p>
<pre><code>NS = "{http://webservices.amazon.com/AWSECommerceService/2010-11-01}"
doc = ET.fromstring(XML)
items = doc[1] # Items element
first_item = items.find(NS + 'Item') # First direct Item child
all_items = items.findall(NS + 'Item') # List of all direct Item children
</code></pre>