这是微信的demo:

function curl_post_ssl($url, $vars, $second=30,$aHeader=array()){

$ch = curl_init();
//超时时间
curl_setopt($ch,CURLOPT_TIMEOUT,$second);
curl_setopt($ch,CURLOPT_RETURNTRANSFER, 1);
//这里设置代理，如果有的话
//curl_setopt($ch,CURLOPT_PROXY, '10.206.30.98');
//curl_setopt($ch,CURLOPT_PROXYPORT, 8080);
curl_setopt($ch,CURLOPT_URL,$url);
curl_setopt($ch,CURLOPT_SSL_VERIFYPEER,false);
curl_setopt($ch,CURLOPT_SSL_VERIFYHOST,false);

//以下两种方式需选择一种

//第一种方法，cert 与 key 分别属于两个.pem文件
//默认格式为PEM，可以注释
//curl_setopt($ch,CURLOPT_SSLCERTTYPE,'PEM');
//curl_setopt($ch,CURLOPT_SSLCERT,getcwd().'/cert.pem');
//默认格式为PEM，可以注释
//curl_setopt($ch,CURLOPT_SSLKEYTYPE,'PEM');
//curl_setopt($ch,CURLOPT_SSLKEY,getcwd().'/private.pem');

//第二种方式，两个文件合成一个.pem文件
curl_setopt($ch,CURLOPT_SSLCERT,getcwd().'/all.pem');

if( count($aHeader) >= 1 ){
    curl_setopt($ch, CURLOPT_HTTPHEADER, $aHeader);
}

curl_setopt($ch,CURLOPT_POST, 1);
curl_setopt($ch,CURLOPT_POSTFIELDS,$vars);
$data = curl_exec($ch);
if($data){
    curl_close($ch);
    return $data;
}
else { 
    $error = curl_errno($ch);
    echo "call faild, errorCode:$error\n"; 
    curl_close($ch);
    return false;
}

}

//返回数据
array(6) {
["return_code"]=>
string(7) "SUCCESS"
["return_msg"]=>
string(8) "CA_ERROR"
["mchid"]=>
string(10) "2342424"
["result_code"]=>
string(4) "FAIL"
["err_code"]=>
string(8) "CA_ERROR"
["err_code_des"]=>
string(62) "CA证书出错，请登录微信支付商户平台下载证书"
}