请问这句英文有没语法错误？

错了，so do i，表示“我也这样”。like to do 不是doing，like后面的to 不是介词，所以后面的动词不用ing形式。

整个句子可以试着改为，When I was a child, I didn't like writing. It is stil the same today.

When I was a child,I didn't like writing,so do I now

like doing sth指喜好做某事

有错误

可以修改如下
When I was a child, I didn't like to write, neither do I now.

也可以这样
When I was a child, I didn't like writing, neither do I now.

so do I表示肯定的现在也是

有错误:Like后面直接加Doing,I didn't like writing

前面是否定。后面是肯定承接。把so改为neither

Like to do sth或者Like doing sth
肯定的So do I或者否定的Neither do I只能另起一句。

可以改成：When I was a child, I didn't like to write. Neither do I now.
When I was a child, I didn't like writing. Neither do I now.