using System.Xml;

    public IList GetCollection()
    {
        ArrayList aaaCollection = new ArrayList();
        XmlDocument doc = new XmlDocument();
        doc.Load("xml文件路径");
        XmlNodeList nodeList = doc.GetElementsByTagName("aaa"); //获取aaa节点集合
        foreach (XmlNode node in nodeList)
        {
            aaaCollection.Add(node.InnerText);
        }
        return aaaCollection;
    }