只需删除输出缓冲（
ob_start()和其他）。
仅使用此：
ftp_get($conn_id, "php://output", $file, FTP_BINARY);
虽然如果要添加
Content-Length标题，则必须先使用来查询文件大小
ftp_size：
$conn_id = ftp_connect("ftp.example.com");ftp_login($conn_id, "username", "password");ftp_pasv($conn_id, true);$file_path = "remote/path/file.zip";$size = ftp_size($conn_id, $file_path);header("Content-Type: application/octet-stream");header("Content-Disposition: attachment; filename=" . basename($file_path));header("Content-Length: $size");ftp_get($conn_id, "php://output", $file_path, FTP_BINARY);（添加错误处理）
