str内容是：<use xlink:href="#主冷凝器" transform="translate(34.10799 143.9815)" stroke="#000000" fill="#FFFFFF" id="主冷凝器0" /><use xlink:href="#阀" transform="translate(447.9079 194.7524)" stroke="#000000" fill="#FFFFFF" id="阀0" /><text ID="主冷凝器0压力" font-size="11" x="273" y="319">压力:5.84MPa</text><text ID="主冷凝器0流量" font-size="11" x="273" y="334">流量:244.31kg/s</text></svg>
string regexstr = @"<text[^>]*?>.*?</text>"; //去除table里面的所有内容
string XmlCodeStr = Regex.Replace(str, regexstr, string.Empty, RegexOptions.IgnoreCase);