一般来说，在tomcat启动时就会有版本信息，如：
信息: Initializing Coyote HTTP/1.1 on http-8023
2009-5-6 16:38:09 org.apache.catalina.startup.Catalina load
信息: Initialization processed in 1673 ms
2009-5-6 16:38:10 org.apache.catalina.core.StandardService start
信息: Starting service Catalina
2009-5-6 16:38:10 org.apache.catalina.core.StandardEngine start
信息: Starting Servlet Engine: Apache Tomcat/6.0.16
另外还可以在以下文件中找到，但据tomcat版本不一样，文件位置稍有差异：
Tomcat5：tomcat_home \server\lib\catalina.jar org\apache\catalina\util\ServerInfo.properties
Tomcat6：tomcat_home \lib\catalina.jar org\apache\catalina\util\ServerInfo.properties
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
server.info=Apache Tomcat/6.0.16
server.number=6.0.16.0
server.built=Jan 28 2008 11:35:29