到网上搜索了一下前人的解决办法，大多数都说修改php.ini中的upload_max_filesize，但修改了这个以后，还是提示这个问题；但phpmyadmin在提示这个问题的时候，右下角有一行英文提示，大致意思是说，解决这个问题，可以参考 phpmyadmin文档；直接点击这个链接，phpmyadmin自动查找到了以下说明：

[1.16] I cannot upload big dump files (memory, http or timeout problems).

Starting with version 2.7.0, the import engine has been re–written and these problems should not occur. If possible, upgrade your phpMyAdmin to the latest version to take advantage of the new import features.

The first things to check (or ask your host provider to check) are the values of upload_max_filesize, memory_limit and post_max_size in the php.ini configuration file. All of these three settings limit the maximum size of data that can be submitted and handled by PHP. One user also said that post_max_size and memory_limit need to be larger than upload_max_filesize.

以上文件大致说明的意思就是说，遇到导入过大文件时，首先检查php.ini 配置文件中的以下三个地方，upload_max_filesize, memory_limit 和post_max_size，并且推荐修改的值要稍大于导入的巨大sql数据库文件；依照这个提示，我修改了以上三个在php.ini中的值以后，重启了php环境，再次导入时，虽然 phpmyadmin还是显示导入最大限制：20,480 KB，但巨大的80M数据库文件已经被成功的导入了。