简单的正则表达式：

（1）preg_match("/^(\d{18,18}|\d{15,15}|\d{17,17}x)$/",$id_card)（2）preg_match("/^(\d{6})(18|19|20)?(\d{2})([01]\d)([0123]\d)(\d{3}) (\d|X)?$/",$id_card)（3）preg_match("/(^\d{15}$/)|(\d{17}(?:\d|x|X)$/),$id_card)

2、复杂并且严格一些的验证：

//这个可以验证15位和18位的身份证，并且包含生日和校验位的验证。 //如果有兴趣，还可以加上身份证所在地的验证，就是前6位有些数字合法有些数字不合法。

function isIdCardNo(num){ num = num.toUpperCase(); //身份证号码为15位或者18位，15位时全为数字，18位前17位为数字，最后一位是校验位，可能为数字或字符X。 if (!(/(^\d{15}$)|(^\d{17}([0-9]|X)$)/.test(num))) { alert('输入的身份证号长度不对，或者号码不符合规定！\n15位号码应全为数字，18位号码末位可以为数字或X。'); return false; }//校验位按照ISO 7064:1983.MOD 11-2的规定生成，X可以认为是数字10。//下面分别分析出生日期和校验位var len, re;len = num.length;if (len == 15){re = new RegExp(/^(\d{6})(\d{2})(\d{2})(\d{2})(\d{3})$/);var arrSplit = num.match(re);

//检查生日日期是否正确var dtmBirth = new Date('19' + arrSplit[2] + '/' + arrSplit[3] + '/' + arrSplit[4]);var bGoodDay;bGoodDay = (dtmBirth.getYear() == Number(arrSplit[2])) && ((dtmBirth.getMonth() + 1) == Number(arrSplit[3])) && (dtmBirth.getDate() == Number(arrSplit[4]));if (!bGoodDay){ alert('输入的身份证号里出生日期不对！'); return false;}else{//将15位身份证转成18位//校验位按照ISO 7064:1983.MOD 11-2的规定生成，X可以认为是数字10。 var arrInt = new Array(7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2); var arrCh = new Array('1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2'); var nTemp = 0, i; num = num.substr(0, 6) + '19' + num.substr(6, num.length - 6); for(i = 0; i < 17; i ++) { nTemp += num.substr(i, 1) * arrInt[i]; } num += arrCh[nTemp % 11]; return num; } }if (len == 18){re = new RegExp(/^(\d{6})(\d{4})(\d{2})(\d{2})(\d{3})([0-9]|X)$/);var arrSplit = num.match(re);

//检查生日日期是否正确var dtmBirth = new Date(arrSplit[2] + "/" + arrSplit[3] + "/" + arrSplit[4]);var bGoodDay;bGoodDay = (dtmBirth.getFullYear() == Number(arrSplit[2])) && ((dtmBirth.getMonth() + 1) == Number(arrSplit[3])) && (dtmBirth.getDate() == Number(arrSplit[4]));if (!bGoodDay){alert(dtmBirth.getYear());alert(arrSplit[2]);alert('输入的身份证号里出生日期不对！');return false;}else{//检验18位身份证的校验码是否正确。//校验位按照ISO 7064:1983.MOD 11-2的规定生成，X可以认为是数字10。var valnum;var arrInt = new Array(7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2);var arrCh = new Array('1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2');var nTemp = 0, i;for(i = 0; i < 17; i ++){nTemp += num.substr(i, 1) * arrInt[i];}valnum = arrCh[nTemp % 11];if (valnum != num.substr(17, 1)){alert('18位身份证的校验码不正确！应该为：' + valnum);return false;}return num;}}return false;} 3、严格的验证：var aCity={11:"北京",12:"天津",13:"河北",14:"山西",15:"内蒙古",21:"辽宁",22:"吉林",23:"黑龙江 ",31:"上海",32:"江苏",33:"浙江",34:"安徽",35:"福建",36:"江西",37:"山东",41:"河南",42:"湖北 ",43:"湖南",44:"广东",45:"广西",46:"海南",50:"重庆",51:"四川",52:"贵州",53:"云南",54:"西藏 ",61:"陕西",62:"甘肃",63:"青海",64:"宁夏",65:"新Unbsp;疆",71:"台湾",81:"香港",82:"澳门",91:"国外 "}

function cidInfo(sId){var iSum=0var info=""if(!/^d{17}(d|x)$/i.test(sId))return false;sId=sId.replace(/x$/i,"a");if(aCity[parseInt(sId.substr(0,2))]==null)return "Error:非法地区";sBirthday=sId.substr(6,4)+"-"+Number(sId.substr(10,2))+"-"+Number(sId.substr(12,2));var d=new Date(sBirthday.replace(/-/g,"/"))if(sBirthday!=(d.getFullYear()+"-"+ (d.getMonth()+1) + "-" + d.getDate()))return "Error:非法生日";for(var i = 17;i>=0;i --) iSum += (Math.pow(2,i) % 11) * parseInt(sId.charAt(17 - i),11)if(iSum%11!=1)return "Error:非法证号";return aCity[parseInt(sId.substr(0,2))]+","+sBirthday+","+(sId.substr(16,1)%2?" 男":"女")}document.write(cidInfo("380524198002300016"),"");document.write(cidInfo("340524198002300019"),"")document.write(cidInfo("340524197711111111"),"")document.write(cidInfo("34052419800101001x"),"");