The picture is beautiful than that one.

than前面一定要加比较级！
改完后是The picture is more beautiful than that one.

than前面一定要加比较级more
Having been thoroughly cleaned, the garden looked more beautiful than ever before.
经过彻底清扫之后,这座花园比以住任何时候都美.
I have never seen a girl more beautiful than Mary.
我从未见过比玛丽更为美丽的女孩子。
Mary is more beautiful than anyone else in her company.
玛丽在公司里比其他人都漂亮。

This picture is more beautiful than that one

用比较级more beautiful than

我不知道这样对不对
This picture is more beautiful than that one